The Central Pacific laid of track, starting in Sacramento, California, in 1863 and continuing over the rugged [[Sierra Nevada (U.S.)|Sierra Nevada]] mountains at [[Donner Pass]] into the new state of Nevada. The elevation change from Sacramento (elev. ) to [[Donner Summit]] (elev. ) had to be accomplished in about with an average elevation change of 76 feet per mile (14 meters per km), and there were only a few places in the Sierra where this type of ramp existed. The discovery and detailed map survey with profiles and elevations of this route over the Sierra Nevada is credited to [[Theodore Judah]], chief engineer of the Central Pacific Railroad until his death in 1863. This route is up a ridge between the North fork of the [[American River]] on the south and [[Bear River (Feather River)]] and [[South Yuba River]] on the north. As the railroad climbed out of Sacramento up to Donner Summit, there was only one section near Cape Horn CPRR where the railroad grade slightly exceeded two percent.