History: Rail Transportation In The United States

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.