Map, Territory of the United States from the Mississippi River to the Pacific Ocean, compiled by G.K. Warren et al.,1858
With appropriations from Congress, Secretary of War Jefferson Davis commissioned the Army Corps of Engineers to explore four routes from the Mississippi River to the Pacific Ocean. This map, published with their report, incorporated information from many previous expeditions. To aid Congress in selecting a route, it indicated locations of settlements, American Indian nations, and military posts.
Geography and Map Division, Library of Congress
A Railroad to the Pacific - 2
Settlement of the western territories in the 1850s increased the need for efficient rail transport to the Pacific Coast, but members of Congress could not agree on what route it should follow. Northern members wanted a northern route; southern members sought one advantageous to their region's interests. To inform this debate, in 1853 Congress authorized the Army Corps of Engineers to survey four potential rail routes. Intense sectionalism blocked further legislation until southern states seceded. In 1862, a northern-controlled Congress passed the Pacific Railroad Act.