1862 - Congress passes the Pacific Railroad act (National Archives).
1863 - The Union Pacific makes all the way to Omaha Nebraska (Shmoop.com).
1865 - The first tracks are laid in Omaha Nebraska (Shmoop.com).
1867 - The Union Pacific massacures hundreds of Native Americans after they try and sabatoge the railroad because they were losing their land ("The Transcontinental Railroad").
1869 - The last spike is nailed in completeing the Transcontinental Railroad (Shmoop.com).