Transcontinental railroad is completed, May 10, 1869

Under the aegis of President Thomas Jefferson, The Corps of Discovery, led by Meriwether Lewis and William Clark, prepared the first maps and reports describing the topography of the trails and passages from the Mississippi River to the Pacific Ocean.

Congress, grasping the importance of such studies to westward expansion, authorized a Corps of Topographical Engineers in 1838. In the 1850s, the Senate ordered the printing of 10,000 copies of topographical surveys, called the Pacific Railroad Route Reports, including one by John Charles Fremont, a member of the corps.

Expansionist-minded legislators such as Sen. Thomas Hart Benton (D-Mo.), Fremont’s father-in-law, saw that railroad builders would rely on such reports to cross the continent and accomplish what many politicians then regarded as the nation’s manifest destiny — unity from Atlantic to Pacific.

Congressional leaders had also recognized that, in the event of a war between the North and the South, whichever side had the best transportation system and access to the West would hold a great military advantage.

Several members of Congress owned stock in The Credit Mobilier of America, formed in 1864 as the agent for the construction of the Union Pacific Railway’s portion of the transcontinental line. In 1868, Rep. Oakes Ames (R-Mass.) distributed shares to his fellow lawmakers, along with cash bribes — though the scandal did not come to light until 1872.

SOURCE: U.S. LIBRARY OF CONGRESS