<P> The Central Pacific Railroad (CPRR) was a rail route between California and Utah built eastwards from the West Coast in the 1860s, to complete the western part of the "First Transcontinental Railroad" in North America . It later became part of the Union Pacific Railroad . </P> <P> Many 19th century national proposals to build a transcontinental railroad failed because of the energy consumed by political disputes over slavery . With the secession of the South, the modernizers in the Republican Party controlled the US Congress . They passed legislation authorizing the railroad, with financing in the form of government railroad bonds . These were all eventually repaid with interest . The government and the railroads both shared in the increased value of the land grants, which the railroads developed . The construction of the railroad also secured for the government the economical "safe and speedy transportation of the mails, troops, munitions of war, and public stores ." </P> <P> Planned by Theodore Judah, the Central Pacific Railroad was authorized by Congress in 1862 . It was financed and built through "The Big Four" (who called themselves "The Associates"): Sacramento, California businessmen Leland Stanford, Collis Huntington, Charles Crocker, and Mark Hopkins . Crocker was in charge of construction . Construction crews comprised 12,000 Chinese emigrant workers by 1868, when they constituted eighty percent of the entire work force . They laid the first rails in 1863 . The "Golden spike", connecting the western railroad to the Union Pacific Railroad at Promontory, Utah, was hammered on May 10, 1869 . Coast - to - coast train travel in eight days became possible, replacing months - long sea voyages and lengthy, hazardous travel by wagon trains . </P> <P> In 1885 the Central Pacific Railroad was leased by the Southern Pacific Company . Technically the CPRR remained a corporate entity until 1959, when it was formally merged into Southern Pacific . (It was reorganized in 1899 as the Central Pacific "Railway".) The original right - of - way is now controlled by the Union Pacific, which bought Southern Pacific in 1996 . </P>

Who made up the labor force of the central pacific railroad while it was being built