William H. Emory & U.S. Army Corp of Topographical Engineers, Boundary between the United States and Mexico (1853)

The 1848 Treaty of Guadalupe Hidalgo ended the Mexican-American War, granting the United States the state of Texas, 525,000 square miles of additional land, and a new 2,000-mile border with Mexico along the Rio Grande and Gila River. However, much of this border remained uncharted or inaccurately mapped, requiring topographical engineers to survey it more precisely. These four maps, created by William Emory and the United States Army Corps of Topographical Engineers, depict some of their findings from these surveying missions. These maps provided more accurate information on the boundaries between Mexico and the United States, improving upon John Disturnell’s Mapa de los Estados Unidos de Méjico, which had been used as a reference while negotiating the treaty, but contained many inaccuracies.