It took 6 years to build the Transcontinental Railroad. It was built between 1863 and 1869 and it measured 1,776 miles in length. This was the first time that the Atlantic and Pacific coasts were connected by railroad in the United States.
Two companies built the Transcontinental Railroad. Central Pacific Railroad started building the railroad in Sacramento, Calif., while Union Pacific Railroad, started building in Omaha, Nebr. The companies finally met on May 10, 1869 in Promontory, Utah. The railroad was the idea of President Abraham Lincoln, but it was not completed until 4 years after his assassination.