 The survey's main goal was to make topographic maps of the southwestern United States.In addition he was to ascertain everything related to the physical features of the region; discover the numbers, habits, and disposition of Indians in the section; select sites for future military installations; determine facilities available for making rail or common roads; and note mineral resources, climate, geology, vegetation, water sources, and agricultural potential.Photographers on the expedition included Timothy H. O'Sullivan of New York and William Bell of Philadelphia.