The Union Pacific Railroad emerged in 1862 under the Pacific Railroad Act. The Act of Congress initiated the construction of railroads west of the Missouri River, in an effort to control western resources during the American Civil War.
The Union Pacific was constructed west from Council Bluffs, Iowa. At the same time the Central Pacific was laid out east from San Francisco. The two lines met up at Promontory Summit in Utah in 1869 to much fanfare.
This map published in 1867 shows cities, towns, forts, waterways, and Indian reservations. Mineral deposits are indicated along with railroad routes, both completed and projected.