<P> The First Transcontinental Railroad (known originally as the "Pacific Railroad" and later as the "Overland Route") was a 1,912 - mile (3,077 km) continuous railroad line constructed between 1863 and 1869 that connected the existing eastern U.S. rail network at Omaha, Nebraska / Council Bluffs, Iowa with the Pacific coast at the Oakland Long Wharf on San Francisco Bay . The rail line was built by three private companies over public lands provided by extensive US land grants . Construction was financed by both state and US government subsidy bonds as well as by company issued mortgage bonds . The Western Pacific Railroad Company built 132 mi (212 km) of track from Oakland / Alameda to Sacramento, California . The Central Pacific Railroad Company of California (CPRR) constructed 690 mi (1,110 km) eastward from Sacramento to Promontory Summit, Utah Territory (U.T.). The Union Pacific built 1,085 mi (1,746 km) from the road's eastern terminus at Council Bluffs near Omaha, Nebraska westward to Promontory Summit . </P> <P> The railroad opened for through traffic on May 10, 1869 when CPRR President Leland Stanford ceremonially drove the gold "Last Spike" (later often referred to as the "Golden Spike") with a silver hammer at Promontory Summit . The coast - to - coast railroad connection revolutionized the settlement and economy of the American West . It brought the western states and territories into alignment with the northern Union states and made transporting passengers and goods coast - to - coast considerably quicker and less expensive . </P>

Where did they start building the transcontinental railroad