Question: who built the first railroad across the us

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 built 132 mi of track from Oakland/Alameda to Sacramento, California.  The Central Pacific Railroad Company of California constructed 690 mi eastward from Sacramento to Promontory Summit, Utah Territory.  The Union Pacific built 1,085 mi from the road's eastern terminus at Council Bluffs near Omaha, Nebraska westward to Promontory Summit.