Andrew Belcher Gray was an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 surveyor

Surveying

See Also: Public Land Survey SystemSurveying or land surveying is the technique, profession, and science of accurately determining the terrestrial or three-dimensional position of points and the distances and angles between them...

.

He studied engineering and surveying under Andrew Talcott

Andrew Talcott

Andrew Talcott was an American civil engineer and close friend of Civil War General Robert E. Lee. While serving as a Confederate States of America Colonel and the State Engineer of Virginia, he was arrested and made prisoner of war during that conflict.-Early life:Talcott was born on April 20,...

, and surveyed the Mississippi Delta

Mississippi Delta

The Mississippi Delta is the distinctive northwest section of the U.S. state of Mississippi that lies between the Mississippi and Yazoo Rivers. The region has been called "The Most Southern Place on Earth" because of its unique racial, cultural, and economic history...

 with him in 1839, before joining the Texas Navy

Texas Navy

The Texas Navy was the official navy of the Republic of Texas. Two Texas Navies were naval fighting forces. There is a “Third and Honorary” Texas Navy, in which officers are commissioned by the Governor of Texas as Admirals, Commanders and Lieutenants....

 as a midshipman

Midshipman

A midshipman is an officer cadet, or a commissioned officer of the lowest rank, in the Royal Navy, United States Navy, and many Commonwealth navies. Commonwealth countries which use the rank include Australia, New Zealand, South Africa, India, Pakistan, Singapore, Sri Lanka and Kenya...

. Remaining in Texas, he was appointed a surveyor for the boundary commission led by Memucan Hunt

Memucan Hunt, Jr.

Memucan Hunt was the first Minister of Texas to the United States, Secretary of the Texas Navy, and an unsuccessful candidate for Vice-President of the Republic of Texas.-Early life:Hunt was born on August 7, 1806...

, and then employed on a survey of the Keeweenaw Peninsula in Michigan, before returning to Texas during the Mexican–American War

Mexican–American War

The Mexican–American War, also known as the First American Intervention, the Mexican War, or the U.S.–Mexican War, was an armed conflict between the United States and Mexico from 1846 to 1848 in the wake of the 1845 U.S...

. Following the war, he served as chief surveyor of the US–Mexican commission which established the border after the Treaty of Guadalupe Hidalgo

Treaty of Guadalupe Hidalgo

The Treaty of Guadalupe Hidalgo is the peace treaty, largely dictated by the United States to the interim government of a militarily occupied Mexico City, that ended the Mexican-American War on February 2, 1848...

; he opposed using the Rio Grande

Rio Grande

The Rio Grande is a river that flows from southwestern Colorado in the United States to the Gulf of Mexico. Along the way it forms part of the Mexico – United States border. Its length varies as its course changes...

 as the border, and was removed from the commission following a dispute with John Bartlett

John Russell Bartlett

John Russell Bartlett was an American historian and linguist.-Biography:Bartlett was born in Providence, Rhode Island...

 over this issue, to be replaced by William Emory.

He then traveled to California in 1849, where he surveyed the site of San Diego. In 1852 he was recruited by the Texas Western Railroad to lead a survey from San Antonio westwards towards the Colorado River

Colorado River

The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states...

 and California; his journals were published in 1856 as Survey of a Route for the Southern Pacific R.R. on the 32nd Parallel

32nd parallel north

The 32nd parallel north is a circle of latitude that is 32 degrees north of the Earth's equatorial plane. It crosses Africa, Asia, the Pacific Ocean, North America and the Atlantic Ocean....

. He settled in Tucson, Arizona

Tucson, Arizona

Tucson is a city in and the county seat of Pima County, Arizona, United States. The city is located 118 miles southeast of Phoenix and 60 miles north of the U.S.-Mexico border. The 2010 United States Census puts the city's population at 520,116 with a metropolitan area population at 1,020,200...

, continuing his surveying business, before joining the Confederate States Army

Confederate States Army

The Confederate States Army was the army of the Confederate States of America while the Confederacy existed during the American Civil War. On February 8, 1861, delegates from the seven Deep South states which had already declared their secession from the United States of America adopted the...

 on the outbreak of the American Civil War

American Civil War

The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

. He worked as an engineer on fortifications 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 was killed in 1862 when the boiler of a steamboat he was traveling on exploded.