Union County is a county

County (United States)

In the United States, a county is a geographic subdivision of a state , usually assigned some governmental authority. The term "county" is used in 48 of the 50 states; Louisiana is divided into parishes and Alaska into boroughs. Parishes and boroughs are called "county-equivalents" by the U.S...

 located in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Arkansas

Arkansas

Arkansas is a state located in the southern region of the United States. Its name is an Algonquian name of the Quapaw Indians. Arkansas shares borders with six states , and its eastern border is largely defined by the Mississippi River...

. As of 2010, the population was 41,639. The county seat

County seat

A county seat is an administrative center, or seat of government, for a county or civil parish. The term is primarily used in the United States....

 is El Dorado

El Dorado, Arkansas

El Dorado , a multi-cultural arts center: South Arkansas Arts Center , an award-winning renovated downtown, and numerous sporting, shopping, and dining opportunities. El Dorado is the population, cultural, and business center of the 7,300 mi² regional area...

. The county was formed on November 2, 1829, and named in recognition of the citizens' petition for a new county, stating that they were petitioning "in the spirit of Union and Unity".

The El Dorado Micropolitan Statistical Area includes all of Union County.
In 1931, a monument was established at the Union County border with Union Parish

Union Parish, Louisiana

Union Parish is a parish located in the U.S. state of Louisiana. The parish seat is Farmerville....

, Louisiana

Louisiana

Louisiana is a state located in the southern region of the United States of America. Its capital is Baton Rouge and largest city is New Orleans. Louisiana is the only state in the U.S. with political subdivisions termed parishes, which are local governments equivalent to counties...

, through the private efforts of former Arkansas Governor George Washington Donaghey

George Washington Donaghey

George Washington Donaghey was the 22nd Governor of the U.S. state of Arkansas from 1909 to 1913.George W. Donaghey was born in Oakland, Union Parish, Louisiana. From 1882 to 1883, Donaghey attended the University of Arkansas. He was a school teacher, carpenter, and studied both architecture and...

 (1856–1937), who was born in Union Parish and grew up in the border area before he moved as a teenager to Conway

Conway, Arkansas

Conway is the county seat of Faulkner County, Arkansas, United States. The population was 58,908 at the 2010 census, making Conway the seventh most populous city in Arkansas. It is a principal city of the Little Rock–North Little Rock–Conway Metropolitan Statistical Area which had...

, Arkansas.