Geography of Illinois
Encyclopedia
Illinois
is in the north-central United States
. Surrounding states are Wisconsin
to the north, Iowa
and Missouri
to the west, Kentucky
to the south, and Indiana
to the east. Illinois also borders Michigan
, but only via a water boundary in Lake Michigan
. Nearly the entire western boundary is the Mississippi River
, except for a few areas where the river has changed course.
" but with political developments since World War II "Downstate" generally refers to all of Illinois outside of the Chicago metro area.
, dominated by the Chicago metropolitan area, including the city of Chicago, its suburbs, and the adjoining exurban area into which the metropolis is expanding. The "collar counties
" are the five counties that surround the centrally located Cook County in the Chicago metropolitan area: DuPage County, Kane County, Lake County, McHenry County, and Will County.
As defined by the federal government, the Chicago metro area includes a few counties in Indiana and Wisconsin and stretches across much of northeastern Illinois, but not as far as Rockford
, generally along Interstates 80
and 90
. The region is cosmopolitan, densely populated, industrialized, and settled by a wide variety of ethnic groups. The term "Chicagoland" is sometimes used to describe the metro area, including Chicago, its suburbs within Cook County, and the so-called collar counties. The term is said to have been coined by Chicago Tribune
publisher Robert R. McCormick
. The Chicagoland Chamber of Commerce
defines it as all of Cook, and DuPage, Kane, Lake, McHenry and Will counties.
In extreme northwestern Illinois the Driftless Zone, a region of unglaciated and therefore higher and more rugged topography, occupies a small part of the state. Charles Mound
, located in this region, is the state's highest elevation above sea level
.
, an area of mostly flat prairie
with the exception of areas along the Illinois and Mississippi rivers that are steeped in hills and bluffs hanging high above the rivers providing commanding views for miles. The western section (west of the Illinois River) was originally part of the Military Tract of 1812
and forms the distinctive western bulge of state. Central Illinois is characterized by small towns and mid-sized cities. Agriculture, particularly corn
and soybeans, figures prominently. Major cities include Peoria
, and Springfield
(the state capital). The Champaign-Urbana Metropolitan Area
is located in the central region of the state and is composed of (Champaign
, Ford, and Piatt
) counties, the area had a population of 210,275 at the 2000 census
It is centered at the University of Illinois
).
, and including Little Egypt
, near the juncture of the Mississippi River
and Ohio River
. This region can be distinguished from the other two by its warmer climate, different mix of crops (including cotton
farming in the past), more rugged unglaciated topography, as well as small-scale oil deposits and coal
mining. The population in southern Illinois is concentrated in two areas:
The Shawnee Hills
arise in southern Illinois. Illinoian Stage, about 132,000 to 300,000 years before present, climbed the northern face of the Shawnee Hills, but did not reach the summit. Most of the Shawnee Hills is therefore unglaciated.
The floodplain on the Mississippi River from Alton
to the Kaskaskia River
is the American Bottom
, and is the site of the ancient city of Cahokia
, and was a region of early French settlement, as well as the site of the first state capital, at Kaskaskia
. The extreme southern tip of Illinois is in the Gulf Coastal Plain
.
. While this tendency has historically been balanced by Republican
voters in the suburbs, Democrats have significantly increased their suburban support in the past decade. Central Illinois' largely rural character helps to sustain a largely Republican voting pattern and widespread antipathy toward Chicago. The combination of poorer soil, coal mining and industrialization has caused the southern region to lean Democratic politically, especially in the urbanized region around Saint Louis
, Missouri
.
Rockford, Illinois
is known as a center of liberal "gypsy moth" Republicans.
", and is the most common type of soil on the planet. The visible geology of the State is therefore mainly Quaternary
, with rocks buried deeply. The wealth of the State mainly arises from this abundance of soil.
Illinois is a major coal
-producing state. Much of the bedrock surface is of Pennsylvanian
age, including "cyclothemes", regular sequences of limestone, shale and coal layers. Newer rocks may have once existed in the State, but these have been removed by repeated epochs of glaciation. Only tiny areas of newer bedrock exist. The chance of finding dinosaur bones in Illinois is almost nil: the Pennsylvanian rocks were here before the dinosaurs.
Galena
, a lead
ore, has been mined in the northwest corner of the State. The ore was processed around Peru, Illinois
, where river transport was available to bring the ore to a source of coal. About six tons of coal are needed for each ton of ore.
Fluorite
, calcium fluoride, is the State mineral. It is mined in the southeastern portion of the State, around Metropolis
. Fluorine gas is produced from fluorite. This is used in the production of uranium hexafluoride
at the gaseous diffusion
plant in Paducah, Kentucky
.
Geode
s can be found in the older Mississippian outcroppings along the Mississippi River
.
Igneous intrusions are found in the far southern areas of the State. Ages ago North America began to split roughly along the lines of the Ohio and Mississippi Rivers. Igneous rock flowed up into fissures, as a new ocean began to form. Had this continued, Illinois might have resembled the Arabian Peninsula
, a broken terrain between two continents. This split, however, failed: the continent reclosed, leaving only a few igneous intrusions, and some oil fields, as evidence that it happened.
North of the Illinois River
the bedrock surface is much older Ordovician
sandstone. This sandstone yields ancient sand that is very useful in the production of glass, and in making molds for metal castings.
belongs to the Pennsylvanian
period, particularly the downstate region. About 68% of the state has coal
-bearing strata of this geologic period. According to the Illinois State Geological Survey, 211 billion tons of bituminous coal
are estimated to lie under the surface, having a total heating value greater than the estimated oil deposits in the Arabian Peninsula
. However, this coal has a high sulfur
content and as such requires special equipment to reduce air pollution.
bisects the state. A few rivers, including the Fox
and Rock
Rivers enter the State from Wisconsin. The Iroquois
and Kankakee
arise in Indiana
, but lose their identity before reaching the Mississippi
. The North Fork of the Vermilion River arises in Indiana, but joins the Vermilion
, which exits the state before joining the Wabash River
in Indiana.
The Mahomet Aquifer
is a large aquifer used as a source for public water supply by many communities in Central Illinois.
species currently found in Illinois include whitetail deer and coyote
, with the latter becoming urbanized in the Chicago
area, as well as common in the rural areas. Furbearers commonly found include opossum, raccoon
, mink
, red
and gray fox
es, and muskrat
. Commonly seen lagomorphs include the cottontail rabbit
and commonly seen rodents include squirrel
s. Game birds found include Canada goose
, mallard duck, ruffed grouse
, wild turkey
, and bobwhite quail
. The cardinal
is the official state bird. The state has approximately 300 species of birds, many of which migrate on the Mississippi Flyway
. Extensive wetland restoration along the Mississippi River
and Illinois River
are attracting many species.
About two thirds of the state was originally prairie, with much of the area converted to rowcrop farming, while the southern third of the state remains heavily forested with oak
, hickory
, and maple
. Also, several prairie plants.
Especially in the northern third of the state, intensive agriculture has made some species rare, while population numbers are increasing in the less-developed south. Large mammals no longer found
in Illinois include American Bison
, Gray Wolf
, American Black Bear
, and elk
.
, with large temperature extremes not moderated by either mountains or oceans. Weather is influenced primarily by cold Canadian Arctic air in the winter, and warm, humid air from the Gulf of Mexico
in the summer. High temperatures in the south of the state are about 10 to 12 °F. warmer than the north. Average annual temperature is 47 °F. in the north and 58 °F. in the south. Temperatures greater than 90 °F. occur about 45 days per year in the south, and 12 days per year in the north. Temperatures below zero °F. occur one day or less per year in the south, and 12 days per year in the north. Annual rainfall is 34 inches (86.4 cm) in the north and 46 inches (116.8 cm) in the south.
Prevailing winds
are from the west. Average wind speeds "blowing off the prairie
" are greater in the Chicago
area. Statewide, the wind speeds average 8 to 12 mph (3.6 to 5.4 ),and is greater in the winter than in summer.
Snowfall averages 30 inches (76.2 cm) in the north and 10 inches (25.4 cm) in the south, although the actual snowfalls vary greatly by year. In some years, southern Illinois receives very little snowfall, and may never get typical winter weather.
Most of the state has four distinct seasons. The southernmost part of the state is heavily forested and the trees are noted for having beautiful fall
colors.
Tornado
es are a common hazard, primarily in the central part of the state, with peak months in June and April. Freezing rain is most common in central Illinois.
is the nominal western boundary of the state, except for locations where the river has changed course. Kaskaskia, Illinois
, the first state capital, is now west of the river. The Mississippi, due to a flood, destroyed the old town of Kaskaskia, and occupies what was the lower channel of the Kaskaskia River
. A portion of Missouri
is east of the river, near Grand Tower, Illinois
. Similar "avulsions
" are found along the Ohio River
border with Kentucky
and the Wabash River
border with Indiana
.
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
is in the north-central United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Surrounding states are Wisconsin
Wisconsin
Wisconsin is a U.S. state located in the north-central United States and is part of the Midwest. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north. Wisconsin's capital is...
to the north, Iowa
Iowa
Iowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
and Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
to the west, Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
to the south, and Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
to the east. Illinois also borders Michigan
Michigan
Michigan is a U.S. state located in the Great Lakes Region of the United States of America. The name Michigan is the French form of the Ojibwa word mishigamaa, meaning "large water" or "large lake"....
, but only via a water boundary in Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
. Nearly the entire western boundary is the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
, except for a few areas where the river has changed course.
Statistics
- Illinois has a maximum north-south distance of 390 miles (627.6 km) and 210 miles (338 km) east-west.
- Total area is 57918 square miles (150,006.9 km²), ranked 25th in size of the 50 states.
- Water area is 2325 square miles (6,021.7 km²); Lake MichiganLake MichiganLake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
accounts for most of this. - Charles MoundCharles MoundCharles Mound is a gentle, high hill in northern Jo Daviess County, Illinois, near the small town of Scales Mound and northeast of Galena. It is the highest natural point in the state; thus, it is considered a highpoint.- Geography :...
is the highest point in the state at 1235 feet (376.4 m) above sea level. - The Mississippi RiverMississippi RiverThe Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
at Cairo, IllinoisCairo, IllinoisCairo is the southernmost city in the U.S. state of Illinois. It is the county seat of Alexander County. Cairo is located at the confluence of the Mississippi and Ohio rivers. The rivers converge at Fort Defiance State Park, an American Civil War fort that was commanded by General Ulysses S. Grant...
is the lowest point, at 279 feet (85 m). - Average elevation is 600 feet (182.9 m) above sea level.
- McLean CountyMcLean County, IllinoisMcLean County is a county in the U.S. state of Illinois. McLean County is included in the Bloomington–Normal, Illinois Metropolitan Statistical Area. According to the 2010 census, it has a population of 169,572, which is an increase of 12.7% from 150,433 in 2000. Its county seat is...
is the largest county in terms of land area (1,184 sq mi.), while Cook CountyCook County, IllinoisCook County is a county in the U.S. state of Illinois, with its county seat in Chicago. It is the second most populous county in the United States after Los Angeles County. The county has 5,194,675 residents, which is 40.5 percent of all Illinois residents. Cook County's population is larger than...
is the largest county in terms of population (5,327,777, as of 2004).
Geographical divisions
Illinois has three major geographical divisions: Northern, Central, and Southern. Collectively, central and southern Illinois are often referred to within Illinois as "downstate IllinoisDownstate Illinois
Downstate Illinois refers to all of Illinois outside of the Chicago metropolitan area. This term is flexible, but because it is generally meant to refer to everything outside the Chicago-area, some cities in Northern Illinois, such as Rockford and DeKalb, , are considered to be "downstate".The term...
" but with political developments since World War II "Downstate" generally refers to all of Illinois outside of the Chicago metro area.
Northern Illinois
The first is Northern IllinoisNorthern Illinois
Northern Illinois is a region generally covering the northern third of the U.S. state of Illinois.-Economics:Northern Illinois is dominated by the metropolitan areas of Chicago, Rockford, and the Quad Cities, which contain a majority of Illinois' population and economic activity, including...
, dominated by the Chicago metropolitan area, including the city of Chicago, its suburbs, and the adjoining exurban area into which the metropolis is expanding. The "collar counties
Collar counties
The collar counties are the five counties of Illinois that border on Chicago's Cook County. The collar counties are tied to Chicago economically, but, like many suburban areas in the United States, have very different political leanings than does the core city...
" are the five counties that surround the centrally located Cook County in the Chicago metropolitan area: DuPage County, Kane County, Lake County, McHenry County, and Will County.
As defined by the federal government, the Chicago metro area includes a few counties in Indiana and Wisconsin and stretches across much of northeastern Illinois, but not as far as Rockford
Rockford, Illinois
Rockford is a mid-sized city located on both banks of the Rock River in far northern Illinois. Often referred to as "The Forest City", Rockford is the county seat of Winnebago County, Illinois, USA. As reported in the 2010 U.S. census, the city was home to 152,871 people, the third most populated...
, generally along Interstates 80
Interstate 80
Interstate 80 is the second-longest Interstate Highway in the United States, following Interstate 90. It is a transcontinental artery running from downtown San Francisco, California to Teaneck, New Jersey in the New York City Metropolitan Area...
and 90
Interstate 90
Interstate 90 is the longest Interstate Highway in the United States at . It is the northernmost coast-to-coast interstate, and parallels US 20 for the most part. Its western terminus is in Seattle, at Edgar Martinez Drive S. near Safeco Field and CenturyLink Field, and its eastern terminus is in...
. The region is cosmopolitan, densely populated, industrialized, and settled by a wide variety of ethnic groups. The term "Chicagoland" is sometimes used to describe the metro area, including Chicago, its suburbs within Cook County, and the so-called collar counties. The term is said to have been coined by Chicago Tribune
Chicago Tribune
The Chicago Tribune is a major daily newspaper based in Chicago, Illinois, and the flagship publication of the Tribune Company. Formerly self-styled as the "World's Greatest Newspaper" , it remains the most read daily newspaper of the Chicago metropolitan area and the Great Lakes region and is...
publisher Robert R. McCormick
Robert R. McCormick
Robert Rutherford "Colonel" McCormick was a member of the McCormick family of Chicago who became owner and publisher of the Chicago Tribune newspaper...
. The Chicagoland Chamber of Commerce
Chicagoland Chamber of Commerce
The Chicagoland Chamber of Commerce is a non-profit organization promoting business in the Chicago metropolitan area of the United States. The Chamber is a voice at local, state and national levels for approximately 2,600 member companies and their 1.3 million employees...
defines it as all of Cook, and DuPage, Kane, Lake, McHenry and Will counties.
- The Quad Cities Metropolitan AreaQuad Cities Metropolitan AreaThe Quad Cities Metropolitan Area, more formally known as the Davenport-Moline-Rock Island Metropolitan Statistical Area is the metropolitan area associated with the Quad Cities and its suburbs...
is on both sides of the Mississippi RiverMississippi RiverThe Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
separating Illinois from IowaIowaIowa is a state located in the Midwestern United States, an area often referred to as the "American Heartland". It derives its name from the Ioway people, one of the many American Indian tribes that occupied the state at the time of European exploration. Iowa was a part of the French colony of New...
. The Illinois side includes Henry CountyHenry County, IllinoisHenry County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 50,486, which is a decrease of 1.0% from 51,020 in 2000. Its county seat is Cambridge...
, Mercer CountyMercer County, IllinoisMercer County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 16,434, which is a decrease of 3.1% from 16,957 in 2000. Its county seat is Aledo...
, and Rock Island CountyRock Island County, IllinoisRock Island County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 147,546, which is a decrease of 1.2% from 149,374 in 2000. Its county seat is Rock Island...
.
In extreme northwestern Illinois the Driftless Zone, a region of unglaciated and therefore higher and more rugged topography, occupies a small part of the state. Charles Mound
Charles Mound
Charles Mound is a gentle, high hill in northern Jo Daviess County, Illinois, near the small town of Scales Mound and northeast of Galena. It is the highest natural point in the state; thus, it is considered a highpoint.- Geography :...
, located in this region, is the state's highest elevation above sea level
Sea level
Mean sea level is a measure of the average height of the ocean's surface ; used as a standard in reckoning land elevation...
.
Central Illinois
Southward and westward, the second major division is Central IllinoisCentral Illinois
Central Illinois is a region of the U.S. state of Illinois that consists of the entire central section of the state, divided in thirds from north to south. It is an area of mostly flat prairie. The western section was originally part of the Military Tract of 1812 and forms the distinctive western...
, an area of mostly flat prairie
Prairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...
with the exception of areas along the Illinois and Mississippi rivers that are steeped in hills and bluffs hanging high above the rivers providing commanding views for miles. The western section (west of the Illinois River) was originally part of the Military Tract of 1812
Military Tract of 1812
In May 1812, an act of Congress was passed which set aside bounty lands as payment to volunteer soldiers for the War against the British...
and forms the distinctive western bulge of state. Central Illinois is characterized by small towns and mid-sized cities. Agriculture, particularly corn
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
and soybeans, figures prominently. Major cities include Peoria
Peoria, Illinois
Peoria is the largest city on the Illinois River and the county seat of Peoria County, Illinois, in the United States. It is named after the Peoria tribe. As of the 2010 census, the city was the seventh-most populated in Illinois, with a population of 115,007, and is the third-most populated...
, and Springfield
Springfield, Illinois
Springfield is the third and current capital of the US state of Illinois and the county seat of Sangamon County with a population of 117,400 , making it the sixth most populated city in the state and the second most populated Illinois city outside of the Chicago Metropolitan Area...
(the state capital). The Champaign-Urbana Metropolitan Area
Champaign-Urbana Metropolitan Area
The Champaign-Urbana metropolitan area, also known as Champaign-Urbana, is a metropolitan area in east-central Illinois. It is the 191st largest metropolitan area in the U.S. It is composed of three counties, Champaign, Ford, and Piatt...
is located in the central region of the state and is composed of (Champaign
Champaign County, Illinois
Champaign County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 201,081, which is an increase of 11.9% from 179,669 in 2000.. It is the 10th most populous county in Illinois...
, Ford, and Piatt
Piatt County, Illinois
Piatt County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 16,729, which is an increase of 2.2% from 16,365 in 2000...
) counties, the area had a population of 210,275 at the 2000 census
United States Census, 2000
The Twenty-second United States Census, known as Census 2000 and conducted by the Census Bureau, determined the resident population of the United States on April 1, 2000, to be 281,421,906, an increase of 13.2% over the 248,709,873 persons enumerated during the 1990 Census...
It is centered at the University of Illinois
University of Illinois at Urbana-Champaign
The University of Illinois at Urbana–Champaign is a large public research-intensive university in the state of Illinois, United States. It is the flagship campus of the University of Illinois system...
).
Southern Illinois
The third division is Southern Illinois, comprising the area south of U.S. Route 50U.S. Route 50
U.S. Route 50 is a major east–west route of the U.S. Highway system, stretching just over from Ocean City, Maryland on the Atlantic Ocean to West Sacramento, California. Until 1972, when it was replaced by Interstate Highways west of the Sacramento area, it extended to San Francisco, near...
, and including Little Egypt
Little Egypt (region)
-Early history:The earliest inhabitants of Illinois were thought to have arrived about 12,000 B.C. They were hunter-gatherers, but developed a primitive system of agriculture. After 1000 AD, their agricultural surpluses enabled them to develop complex, hierarchical societies...
, near the juncture of the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
and Ohio River
Ohio River
The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...
. This region can be distinguished from the other two by its warmer climate, different mix of crops (including cotton
Cotton
Cotton is a soft, fluffy staple fiber that grows in a boll, or protective capsule, around the seeds of cotton plants of the genus Gossypium. The fiber is almost pure cellulose. The botanical purpose of cotton fiber is to aid in seed dispersal....
farming in the past), more rugged unglaciated topography, as well as small-scale oil deposits and coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
mining. The population in southern Illinois is concentrated in two areas:
- Metro-EastMetro-EastMetro East is a region in Illinois that comprises the eastern suburbs of St. Louis, Missouri, United States. It encompasses five Southern Illinois counties in the St. Louis Metropolitan Statistical Area. The region's most populated city is Belleville at 45,000 residents...
is an area east of St. LouisSt. Louis, MissouriSt. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
and it includes (JerseyJersey County, IllinoisJersey County is a county located in the U.S. state of Illinois. Jersey County is part of the St. Louis Metropolitan Area. According to the 2010 census, it has a population of 22,985, which is an increase of 6.1% from 21,668 in 2000...
, MadisonMadison County, IllinoisMadison County is a county located in the U.S. state of Illinois. Madison County is part of the Metro-East region of the St. Louis Metro Area. According to the 2010 census, it has a population of 269,282, which is an increase of 4.0% from 258,941 in 2000. The county seat is Edwardsville, home to...
, St. ClairSt. Clair County, IllinoisSt. Clair County is a county located in the U.S. state of Illinois. In 1970, the U.S. Census Bureau placed the mean center of U.S. population in St. Clair County. According to the 2010 census, it has a population of 270,056, which is an increase of 5.5% from 256,082 in 2000. Its county seat is...
, MacoupinMacoupin County, IllinoisMacoupin County is a county located in the southwestern portion of the U.S. state of Illinois. According to the 2010 census, it has a population of 47,765, which is a decrease of 2.6% from 49,019 in 2000. The county seat is Carlinville. Macoupin County is an outlying county of the Metro-East region...
, and parts of BondBond County, IllinoisBond County is a county located in the U.S. state of Illinois. It is part of the St. Louis Metro Area. According to the 2010 census, it has a population of 17,768, which is an increase of 0.8% from 17,633 in 2000. Its county seat is Greenville, Illinois....
and CalhounCalhoun County, IllinoisCalhoun County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 5,089, which is an increase of 0.1% from 5,084 in 2000. Its county seat is Hardin. It is part of the Metro-East portion of the St...
from the St. Louis Metropolitan Statistical AreaSt. Louis Metropolitan Statistical AreaGreater St. Louis is the area of Missouri and Illinois that surrounds and includes the independent city of St. Louis. Depending on the counties included in the area, it can refer to the St. Louis, MO-IL metropolitan statistical area or the St. Louis-St. Charles-Farmington, MO-IL combined...
, as well as Clinton CountyClinton County, Illinois-Demographics: As of the census of 2000, there were 35,535 people, 12,754 households, and 9,221 families residing in the county. The population density was 75 people per square mile . There were 13,805 housing units at an average density of 29 per square mile...
. - Carbondale, Marion, West Frankfort, Herrin, Murphysboro, Carterville, and the Johnston City area.
The Shawnee Hills
Shawnee Hills
The Shawnee Hills is a region of Southern Illinois that rests mainly in an east-west arc roughly following the outline of the southern end of the Illinois Basin. Whereas Mississippian and Pennsylvania Age rock layers are deep beneath the surface in central Illinois, these strata pierce the surface...
arise in southern Illinois. Illinoian Stage, about 132,000 to 300,000 years before present, climbed the northern face of the Shawnee Hills, but did not reach the summit. Most of the Shawnee Hills is therefore unglaciated.
The floodplain on the Mississippi River from Alton
Alton, Illinois
Alton is a city on the Mississippi River in Madison County, Illinois, United States, about north of St. Louis, Missouri. The population was 27,865 at the 2010 census. It is a part of the Metro-East region of the Greater St. Louis metropolitan area in Southern Illinois...
to the Kaskaskia River
Kaskaskia River
The Kaskaskia River is a tributary of the Mississippi River, approximately long, in central and southern Illinois in the United States. The second largest river system within Illinois, it drains a rural area of farms, as well as rolling hills along river bottoms of hardwood forests in its lower...
is the American Bottom
American Bottom
The American Bottom is the flood plain of the Mississippi River in the Metro-East region of Southern Illinois, extending from Alton, Illinois, to the Kaskaskia River. It is also sometimes called "American Bottoms". The area is about , mostly protected from flooding by a levee and drainage canal...
, and is the site of the ancient city of Cahokia
Cahokia
Cahokia Mounds State Historic Site is the area of an ancient indigenous city located in the American Bottom floodplain, between East Saint Louis and Collinsville in south-western Illinois, across the Mississippi River from St. Louis, Missouri. The site included 120 human-built earthwork mounds...
, and was a region of early French settlement, as well as the site of the first state capital, at Kaskaskia
Kaskaskia, Illinois
Kaskaskia is a village in Randolph County, Illinois, United States. In the 2010 census the population was 14, making it the second-smallest incorporated community in the State of Illinois in terms of population. A major French colonial town of the Illinois Country, its peak population was about...
. The extreme southern tip of Illinois is in the Gulf Coastal Plain
Gulf Coastal Plain
The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico.The plain reaches from the western Florida Panhandle, the southwestern two thirds of Alabama, over most of Mississippi, some of western Tennessee and Kentucky, southwest Arkansas, the Florida...
.
Political geography
The city of Chicago and some of its older suburbs are heavily DemocraticDemocratic Party (United States)
The Democratic Party is one of two major contemporary political parties in the United States, along with the Republican Party. The party's socially liberal and progressive platform is largely considered center-left in the U.S. political spectrum. The party has the lengthiest record of continuous...
. While this tendency has historically been balanced by Republican
Republican Party (United States)
The Republican Party is one of the two major contemporary political parties in the United States, along with the Democratic Party. Founded by anti-slavery expansion activists in 1854, it is often called the GOP . The party's platform generally reflects American conservatism in the U.S...
voters in the suburbs, Democrats have significantly increased their suburban support in the past decade. Central Illinois' largely rural character helps to sustain a largely Republican voting pattern and widespread antipathy toward Chicago. The combination of poorer soil, coal mining and industrialization has caused the southern region to lean Democratic politically, especially in the urbanized region around Saint Louis
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
, Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
.
Rockford, Illinois
Rockford, Illinois
Rockford is a mid-sized city located on both banks of the Rock River in far northern Illinois. Often referred to as "The Forest City", Rockford is the county seat of Winnebago County, Illinois, USA. As reported in the 2010 U.S. census, the city was home to 152,871 people, the third most populated...
is known as a center of liberal "gypsy moth" Republicans.
Geology
Illinois is mainly covered with soil, hundreds of feet thick in many places. Much of this soil is called, appropriately, "IlliteIllite
Illite is a non-expanding, clay-sized, micaceous mineral. Illite is a phyllosilicate or layered alumino-silicate. Its structure is constituted by the repetition of tetrahedron – octahedron – tetrahedron layers. The interlayer space is mainly occupied by poorly hydrated potassium cations...
", and is the most common type of soil on the planet. The visible geology of the State is therefore mainly Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
, with rocks buried deeply. The wealth of the State mainly arises from this abundance of soil.
Illinois is a major coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
-producing state. Much of the bedrock surface is of Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
age, including "cyclothemes", regular sequences of limestone, shale and coal layers. Newer rocks may have once existed in the State, but these have been removed by repeated epochs of glaciation. Only tiny areas of newer bedrock exist. The chance of finding dinosaur bones in Illinois is almost nil: the Pennsylvanian rocks were here before the dinosaurs.
Galena
Galena
Galena is the natural mineral form of lead sulfide. It is the most important lead ore mineral.Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the cubic crystal system often showing octahedral forms...
, a lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
ore, has been mined in the northwest corner of the State. The ore was processed around Peru, Illinois
Peru, Illinois
Peru is a city in LaSalle County, Illinois, United States. The population was 10,295 at the 2010 census. It is part of the Ottawa–Streator Micropolitan Statistical Area...
, where river transport was available to bring the ore to a source of coal. About six tons of coal are needed for each ton of ore.
Fluorite
Fluorite
Fluorite is a halide mineral composed of calcium fluoride, CaF2. It is an isometric mineral with a cubic habit, though octahedral and more complex isometric forms are not uncommon...
, calcium fluoride, is the State mineral. It is mined in the southeastern portion of the State, around Metropolis
Metropolis, Illinois
Metropolis is a city located along the Ohio River in Massac County, Illinois, in the United States. As of the 2000 census, the city population was 6,482...
. Fluorine gas is produced from fluorite. This is used in the production of uranium hexafluoride
Uranium hexafluoride
Uranium hexafluoride , referred to as "hex" in the nuclear industry, is a compound used in the uranium enrichment process that produces fuel for nuclear reactors and nuclear weapons. It forms solid grey crystals at standard temperature and pressure , is highly toxic, reacts violently with water...
at the gaseous diffusion
Gaseous diffusion
Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride through semi-permeable membranes. This produces a slight separation between the molecules containing uranium-235 and uranium-238 . By use of a large cascade of many stages, high separations...
plant in Paducah, Kentucky
Paducah, Kentucky
Paducah is the largest city in Kentucky's Jackson Purchase Region and the county seat of McCracken County, Kentucky, United States. It is located at the confluence of the Tennessee River and the Ohio River, halfway between the metropolitan areas of St. Louis, Missouri, to the west and Nashville,...
.
Geode
Geode
Geodes are geological secondary sedimentary structures which occur in sedimentary and certain volcanic rocks. Geodes are essentially spherical masses of mineral matter that were deposited sygenetically within the rock formations they are found in. Geodes have a Chalcedony shell containing...
s can be found in the older Mississippian outcroppings along the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
.
Igneous intrusions are found in the far southern areas of the State. Ages ago North America began to split roughly along the lines of the Ohio and Mississippi Rivers. Igneous rock flowed up into fissures, as a new ocean began to form. Had this continued, Illinois might have resembled the Arabian Peninsula
Arabian Peninsula
The Arabian Peninsula is a land mass situated north-east of Africa. Also known as Arabia or the Arabian subcontinent, it is the world's largest peninsula and covers 3,237,500 km2...
, a broken terrain between two continents. This split, however, failed: the continent reclosed, leaving only a few igneous intrusions, and some oil fields, as evidence that it happened.
North of the Illinois River
Illinois River
The Illinois River is a principal tributary of the Mississippi River, approximately long, in the State of Illinois. The river drains a large section of central Illinois, with a drainage basin of . This river was important among Native Americans and early French traders as the principal water route...
the bedrock surface is much older Ordovician
Ordovician
The Ordovician is a geologic period and system, the second of six of the Paleozoic Era, and covers the time between 488.3±1.7 to 443.7±1.5 million years ago . It follows the Cambrian Period and is followed by the Silurian Period...
sandstone. This sandstone yields ancient sand that is very useful in the production of glass, and in making molds for metal castings.
Coal
The majority of Illinois surface bedrockBedrock
In stratigraphy, bedrock is the native consolidated rock underlying the surface of a terrestrial planet, usually the Earth. Above the bedrock is usually an area of broken and weathered unconsolidated rock in the basal subsoil...
belongs to the Pennsylvanian
Pennsylvanian
The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...
period, particularly the downstate region. About 68% of the state has coal
Coal
Coal is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure...
-bearing strata of this geologic period. According to the Illinois State Geological Survey, 211 billion tons of bituminous coal
Bituminous coal
Bituminous coal or black coal is a relatively soft coal containing a tarlike substance called bitumen. It is of higher quality than lignite coal but of poorer quality than Anthracite...
are estimated to lie under the surface, having a total heating value greater than the estimated oil deposits in the Arabian Peninsula
Arabian Peninsula
The Arabian Peninsula is a land mass situated north-east of Africa. Also known as Arabia or the Arabian subcontinent, it is the world's largest peninsula and covers 3,237,500 km2...
. However, this coal has a high sulfur
Sulfur
Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
content and as such requires special equipment to reduce air pollution.
Rivers
Illinois is mainly bounded by rivers, and the Illinois RiverIllinois River
The Illinois River is a principal tributary of the Mississippi River, approximately long, in the State of Illinois. The river drains a large section of central Illinois, with a drainage basin of . This river was important among Native Americans and early French traders as the principal water route...
bisects the state. A few rivers, including the Fox
Fox River (Illinois River tributary)
The Fox River is a tributary of the Illinois River in the states of Wisconsin and Illinois in the United States. There are two other "Fox Rivers" in southern Illinois: the Fox River and a smaller "Fox River" that joins the Wabash River near New Harmony, Indiana.-Wisconsin:The Fox River rises near...
and Rock
Rock River (Illinois)
The Rock River is a tributary of the Mississippi River, approximately long, in the U.S. states of Wisconsin and Illinois. It rises in southeast Wisconsin, in the Theresa Marsh near Theresa, Wisconsin in northeast Dodge County, Wisconsin approximately south of Fond du Lac, Wisconsin...
Rivers enter the State from Wisconsin. The Iroquois
Iroquois River
The Iroquois River is a tributary of the Kankakee River in northwestern Indiana and northeastern Illinois in the United States. Via the Kankakee and Illinois rivers, it is part of the watershed of the Mississippi River.-Course:...
and Kankakee
Kankakee River
The Kankakee River is a tributary of the Illinois River, approximately long, in northwestern Indiana and northeastern Illinois in the United States. At one time the river drained one of the largest wetlands in North America and furnished a significant portage between the Great Lakes and the...
arise in Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
, but lose their identity before reaching the Mississippi
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
. The North Fork of the Vermilion River arises in Indiana, but joins the Vermilion
Vermilion River (Wabash River tributary)
The Vermilion River is a tributary of the Wabash River in the states of Illinois and Indiana, United States.There are two "Vermilion Rivers" in Illinois. The Wabash tributary flows south, while the other Vermilion River flows north to the Illinois River...
, which exits the state before joining the Wabash River
Wabash River
The Wabash River is a river in the Midwestern United States that flows southwest from northwest Ohio near Fort Recovery across northern Indiana to southern Illinois, where it forms the Illinois-Indiana border before draining into the Ohio River, of which it is the largest northern tributary...
in Indiana.
- List of Illinois rivers
- Watersheds of IllinoisWatersheds of IllinoisWatersheds of Illinois is a list of basins or catchment areas into which the State of Illinois can be divided based on the place to which water flows....
Groundwater
Subsurface water is generally plentiful in Illinois. However, irregular gravel deposits from glaciation can lead to difficulties predicting depth of the water table.The Mahomet Aquifer
Mahomet Aquifer
The Mahomet Aquifer is the most important aquifer in east-central Illinois. The sand and gravel aquifer is part of the buried Mahomet Bedrock Valley. It underlies 15 counties and ranges from 50 to 200 feet thick...
is a large aquifer used as a source for public water supply by many communities in Central Illinois.
Flora and fauna
Large mammalMammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
species currently found in Illinois include whitetail deer and coyote
Coyote
The coyote , also known as the American jackal or the prairie wolf, is a species of canine found throughout North and Central America, ranging from Panama in the south, north through Mexico, the United States and Canada...
, with the latter becoming urbanized in the Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
area, as well as common in the rural areas. Furbearers commonly found include opossum, raccoon
Raccoon
Procyon is a genus of nocturnal mammals, comprising three species commonly known as raccoons, in the family Procyonidae. The most familiar species, the common raccoon , is often known simply as "the" raccoon, as the two other raccoon species in the genus are native only to the tropics and are...
, mink
Mink
There are two living species referred to as "mink": the European Mink and the American Mink. The extinct Sea Mink is related to the American Mink, but was much larger. All three species are dark-colored, semi-aquatic, carnivorous mammals of the family Mustelidae, which also includes the weasels and...
, red
Red Fox
The red fox is the largest of the true foxes, as well as being the most geographically spread member of the Carnivora, being distributed across the entire northern hemisphere from the Arctic Circle to North Africa, Central America, and the steppes of Asia...
and gray fox
Gray Fox
The gray fox is a mammal of the order Carnivora ranging throughout most of the southern half of North America from southern Canada to the northern part of South America...
es, and muskrat
Muskrat
The muskrat , the only species in genus Ondatra, is a medium-sized semi-aquatic rodent native to North America, and introduced in parts of Europe, Asia, and South America. The muskrat is found in wetlands and is a very successful animal over a wide range of climates and habitats...
. Commonly seen lagomorphs include the cottontail rabbit
Cottontail rabbit
The cottontail rabbits are among the 16 lagomorph species in the genus Sylvilagus, found in the Americas.In appearance, most cottontail rabbits closely resemble the wild European Rabbit...
and commonly seen rodents include squirrel
Squirrel
Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...
s. Game birds found include Canada goose
Canada Goose
The Canada Goose is a wild goose belonging to the genus Branta, which is native to arctic and temperate regions of North America, having a black head and neck, white patches on the face, and a brownish-gray body....
, mallard duck, ruffed grouse
Ruffed Grouse
The Ruffed Grouse is a medium-sized grouse occurring in forests from the Appalachian Mountains across Canada to Alaska. It is non-migratory.The Ruffed Grouse is frequently referred to as a "partridge"...
, wild turkey
Wild Turkey
The Wild Turkey is native to North America and is the heaviest member of the Galliformes. It is the same species as the domestic turkey, which derives from the South Mexican subspecies of wild turkey .Adult wild turkeys have long reddish-yellow to grayish-green...
, and bobwhite quail
Bobwhite Quail
The Northern Bobwhite, Virginia Quail or Bobwhite Quail is a ground-dwelling bird native to the United States, Mexico, and the Caribbean...
. The cardinal
Cardinal (bird)
The Cardinals or Cardinalidae are a family of passerine birds found in North and South America. The South American cardinals in the genus Paroaria are placed in another family, the Thraupidae ....
is the official state bird. The state has approximately 300 species of birds, many of which migrate on the Mississippi Flyway
Mississippi Flyway
The Mississippi Flyway is a bird migration route that generally follows the Mississippi River in the United States and the Mackenzie River in Canada. The main endpoints of the flyway include central Canada and the region surrounding the Gulf of Mexico...
. Extensive wetland restoration along the Mississippi River
Mississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
and Illinois River
Illinois River
The Illinois River is a principal tributary of the Mississippi River, approximately long, in the State of Illinois. The river drains a large section of central Illinois, with a drainage basin of . This river was important among Native Americans and early French traders as the principal water route...
are attracting many species.
About two thirds of the state was originally prairie, with much of the area converted to rowcrop farming, while the southern third of the state remains heavily forested with oak
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, hickory
Hickory
Trees in the genus Carya are commonly known as hickory, derived from the Powhatan language of Virginia. The genus includes 17–19 species of deciduous trees with pinnately compound leaves and big nuts...
, and maple
Maple
Acer is a genus of trees or shrubs commonly known as maple.Maples are variously classified in a family of their own, the Aceraceae, or together with the Hippocastanaceae included in the family Sapindaceae. Modern classifications, including the Angiosperm Phylogeny Group system, favour inclusion in...
. Also, several prairie plants.
Especially in the northern third of the state, intensive agriculture has made some species rare, while population numbers are increasing in the less-developed south. Large mammals no longer found
Local extinction
Local extinction, also known as extirpation, is the condition of a species which ceases to exist in the chosen geographic area of study, though it still exists elsewhere...
in Illinois include American Bison
American Bison
The American bison , also commonly known as the American buffalo, is a North American species of bison that once roamed the grasslands of North America in massive herds...
, Gray Wolf
Gray Wolf
The gray wolf , also known as the wolf, is the largest extant wild member of the Canidae family...
, American Black Bear
American black bear
The American black bear is a medium-sized bear native to North America. It is the continent's smallest and most common bear species. Black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in...
, and elk
Red Deer
The red deer is one of the largest deer species. Depending on taxonomy, the red deer inhabits most of Europe, the Caucasus Mountains region, Asia Minor, parts of western Asia, and central Asia. It also inhabits the Atlas Mountains region between Morocco and Tunisia in northwestern Africa, being...
.
Climate
Illinois has a continental climateContinental climate
Continental climate is a climate characterized by important annual variation in temperature due to the lack of significant bodies of water nearby...
, with large temperature extremes not moderated by either mountains or oceans. Weather is influenced primarily by cold Canadian Arctic air in the winter, and warm, humid air from the Gulf of Mexico
Gulf of Mexico
The Gulf of Mexico is a partially landlocked ocean basin largely surrounded by the North American continent and the island of Cuba. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. In...
in the summer. High temperatures in the south of the state are about 10 to 12 °F. warmer than the north. Average annual temperature is 47 °F. in the north and 58 °F. in the south. Temperatures greater than 90 °F. occur about 45 days per year in the south, and 12 days per year in the north. Temperatures below zero °F. occur one day or less per year in the south, and 12 days per year in the north. Annual rainfall is 34 inches (86.4 cm) in the north and 46 inches (116.8 cm) in the south.
Prevailing winds
WINDS
WINDS , is a Japanese communication satellite. Launch was originally scheduled for 2007. The launch date was eventually set for 15 February 2008, however a problem detected in a second stage manoeuvring thruster delayed it to 23 February...
are from the west. Average wind speeds "blowing off the prairie
Prairie
Prairies are considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type...
" are greater in the Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
area. Statewide, the wind speeds average 8 to 12 mph (3.6 to 5.4 ),and is greater in the winter than in summer.
Snowfall averages 30 inches (76.2 cm) in the north and 10 inches (25.4 cm) in the south, although the actual snowfalls vary greatly by year. In some years, southern Illinois receives very little snowfall, and may never get typical winter weather.
Most of the state has four distinct seasons. The southernmost part of the state is heavily forested and the trees are noted for having beautiful fall
Autumn
Autumn is one of the four temperate seasons. Autumn marks the transition from summer into winter usually in September or March when the arrival of night becomes noticeably earlier....
colors.
Tornado
Tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...
es are a common hazard, primarily in the central part of the state, with peak months in June and April. Freezing rain is most common in central Illinois.
Border anomalies
The Mississippi RiverMississippi River
The Mississippi River is the largest river system in North America. Flowing entirely in the United States, this river rises in western Minnesota and meanders slowly southwards for to the Mississippi River Delta at the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains...
is the nominal western boundary of the state, except for locations where the river has changed course. Kaskaskia, Illinois
Kaskaskia, Illinois
Kaskaskia is a village in Randolph County, Illinois, United States. In the 2010 census the population was 14, making it the second-smallest incorporated community in the State of Illinois in terms of population. A major French colonial town of the Illinois Country, its peak population was about...
, the first state capital, is now west of the river. The Mississippi, due to a flood, destroyed the old town of Kaskaskia, and occupies what was the lower channel of the Kaskaskia River
Kaskaskia River
The Kaskaskia River is a tributary of the Mississippi River, approximately long, in central and southern Illinois in the United States. The second largest river system within Illinois, it drains a rural area of farms, as well as rolling hills along river bottoms of hardwood forests in its lower...
. A portion of Missouri
Missouri
Missouri is a US state located in the Midwestern United States, bordered by Iowa, Illinois, Kentucky, Tennessee, Arkansas, Oklahoma, Kansas and Nebraska. With a 2010 population of 5,988,927, Missouri is the 18th most populous state in the nation and the fifth most populous in the Midwest. It...
is east of the river, near Grand Tower, Illinois
Grand Tower, Illinois
Grand Tower is a city in Jackson County, Illinois, United States. The population was 624 at the 2000 census. The town gets its name from Tower Rock, a landmark island in the Mississippi River.-Geography:Grand Tower is located at ....
. Similar "avulsions
Avulsion (river)
In sedimentary geology and fluvial geomorphology, avulsion is the rapid abandonment of a river channel and the formation of a new river channel. Avulsions occur as a result of channel slopes that are much lower than the slope that the river could travel if it took a new course.-Deltaic and...
" are found along the Ohio River
Ohio River
The Ohio River is the largest tributary, by volume, of the Mississippi River. At the confluence, the Ohio is even bigger than the Mississippi and, thus, is hydrologically the main stream of the whole river system, including the Allegheny River further upstream...
border with Kentucky
Kentucky
The Commonwealth of Kentucky is a state located in the East Central United States of America. As classified by the United States Census Bureau, Kentucky is a Southern state, more specifically in the East South Central region. Kentucky is one of four U.S. states constituted as a commonwealth...
and the Wabash River
Wabash River
The Wabash River is a river in the Midwestern United States that flows southwest from northwest Ohio near Fort Recovery across northern Indiana to southern Illinois, where it forms the Illinois-Indiana border before draining into the Ohio River, of which it is the largest northern tributary...
border with Indiana
Indiana
Indiana is a US state, admitted to the United States as the 19th on December 11, 1816. It is located in the Midwestern United States and Great Lakes Region. With 6,483,802 residents, the state is ranked 15th in population and 16th in population density. Indiana is ranked 38th in land area and is...
.