Andrew Belcher Gray (July 6, 1820 – April 16, 1862) was an American surveyor.
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 Texas, he was appointed a surveyor for the boundary commission led by Memucan Hunt, and then employed on a survey of the Keeweenaw Peninsula in Michigan, before returning to 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; he opposed using the Rio Grande as the border, and was removed from the commission following a dispute with John Bartlett 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 and California; his journals were published in 1856 as Survey of a Route for the Southern Pacific R.R. on the 32nd Parallel. He settled in Tucson, Arizona, continuing his surveying business, before joining the Confederate States Army on the outbreak of the American Civil War. He worked as an engineer on fortifications along the Mississippi River, and was killed in 1862 when the boiler of a steamboat he was traveling on exploded.
- "Gray, Andrew Belcher" in Encyclopedia of Frontier Biography: G-O, by Dan L. Thrapp. University of Nebraska Press, 1991. ISBN 0803294190