 A series of transcontinental railroads built over the last third of the 19th century created a nationwide transportation network that united the country by rail.The first of these, the "Pacific Railroad", was built by the Central Pacific Railroad and Union Pacific Railroad to link the San Francisco Bay at Alameda, California, with the nation's existing eastern railroad network at Council Bluffs, Iowa/Omaha, Nebraska, thereby creating the world's first transcontinental railroad when it opened in 1869.Its construction was made possible by the US government under Pacific Railroad Acts of 1862, 1864, and 1867.