The Transcontinental Railroad
www.archives.gov

... The legislation authorized two railroad companies, the Union Pacific and the Central Pacific, to construct the lines.

Beginning in 1863, the Union Pacific, employing more than 8,000 Irish, German, and Italian immigrants, built west from Omaha, Nebraska; the Central Pacific, whose workforce included over 10,000 Chinese laborers, built eastward from Sacramento, California.

Each company faced unprecedented construction problems"mountains, severe weather, and the hostility of Native Americans.

On May 10, 1869, in a ceremony at Promontory, Utah, the last rails were laid and the last spike driven. Congress eventually authorized 4 transcontinental railroads and granted 174 million acres of public lands for rights-of-way. ...