Question: what were the companies that built the transcontinental railroad

title: First Transcontinental Railroad
text: The First Transcontinental Railroad ( also called the Great 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 . 

Answer: answer: The rail line was built by three private companies: the Western Pacific Railroad Company, the Central Pacific Railroad Company, and the Union Pacific.