History: Rail Transportation In The United States

Authorized by the Pacific Railway Act of 1862 and heavily backed by the federal government, the first transcontinental railroad was the culmination of a decades-long movement to build such a line and was one of the crowning achievements of the presidency of Abraham Lincoln, completed four years after his death. The building of the railroad required enormous feats of engineering and labor in the crossing of plains and high mountains by the Union Pacific Railroad and Central Pacific Railroad, the two federally chartered enterprises that built the line westward and eastward respectively. The building of the railroad was motivated in part to bind the Union together during the strife of the American Civil War. It substantially accelerated the populating of the West by white homesteaders, led to rapid cultivation of new farm lands. The Central Pacific and the Southern Pacific Railroad combined operations in 1870 and formally merged in 1885; the Union Pacific originally bought the Southern Pacific in 1901 and was forced to divest it in 1913, but finally took it over for good in 1996.
Much of the original right-of-way is still in use today and owned by the modern Union Pacific Railroad, which is descended from both of the original railroads.
- Rail gauge selection
Many Canadian and United States railroads originally used various broad gauges, but most were converted to 4 ft 8 1⁄2 in (1,435 mm) by 1886, when the conversion of much of the southern rail network from 5 ft (1,524 mm) gauge took place. This and the standardization of couplings and air brakes enabled the pooling and interchange of locomotives and rolling stock.