The Transcontinental Railroad was completed in 1869, connecting the Union Pacific Railroad from the east to the Central Pacific Railroad from the west. This unprecedented engineering feat joined the Atlantic and Pacific oceans by rail for the first time. While the railroad was built for national defense and to unite the country, it also made a handful of men immensely wealthy, including Leland Stanford, Collis Huntington, Mark Hopkins, and Charles Crocker of the Central Pacific, and Thomas Durant of the Union Pacific. The completion of the Transcontinental Railroad transformed the United States by enabling rapid population growth in the West, spurring additional rail construction, and symbolizing the vast opportunities available in the newly opened western territories.