Andrew Gray

Andrew Belcher Gray (July 6, 1820–April 16, 1862) was an American surveyor.

Born in Norfolk, Virginia, he studied engineering and surveying under Andrew Talcott, and surveyed the Mississippi Delta with him in 1839, before joining the Texas Navy as a midshipman. Remaining in the Republic of Texas, he was appointed a surveyor for the Texas-U.S. boundary commission led by Memucan Hunt. In 1844–1846, he served as U.S. government mineral surveyor, mapping the rich copper country of the Keeweenaw Peninsula in Michigan and leasing out the government's mineral lands.

He returned to the new state of Texas during the Mexican–American War. Following the war, he served as chief surveyor of the US–Mexican commission which established the border after the Treaty of Guadalupe Hidalgo. When the U. S. Commissioner, John Bartlett, a Yankee, gave away the Rio Grande's Mesilla Valley because of a map error, which had been disputed by the Mexican Delegation, the fiery Southerner Gray opposed the unacceptable compromise, and was removed from the commission (as surveyor, his signature was required for approval of the compromise). He was replaced by friend William Emory, but not before Gray had finished surveying the original U.S.–Mexico boundary from the Rio Grande, over the Black Range, down the Gila River to its junction with the Colorado River, and across the desert of southern California to the Pacific Ocean at San Diego. The U.S. Congress reviewing the case sided with Gray, but in the interim the President had sent James Gadsden to Mexico City to buy not just the Mesilla Valley of New Mexico but what is now known as the Gadsden Purchase from Mexico. Gray's claim in his survey report that it was the best route for a railroad influenced the Senate to approve the Treaty in 1854.

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