Boundary Surveys
The Treaty of Guadalupe Hidalgo in 1848 at the end of the United States-Mexico War established the boundary between the two nations, and expanded the United States to the Pacific Ocean. In 1853, the Gadsen Purchase added the area along the modern Arizona-New Mexico-Sonora border to the United States. The expeditions to survey the border between 1848 and 1855 were the rst biological inventories of the borderlands. Many common Sky Islands plants were…