The last link
The Transcontinental Railroad was completed on May 10, 1869, when four ceremonial gold and silver spikes were driven into a laurel wood railroad tie at Promontory Summit, northwest of Salt Lake City, Utah. This act joined 1,776 miles of rail belonging to the Union and Central Pacific railroads. The Union Pacific’s engine, 119, is on the left; the Central Pacific’s Jupiter is on the right. The ceremonial spikes and tie were removed and replaced with iron and pine. Text adapted from “Evaluating Perspectives on Westward Expansion: Weighing the Evidence” in the special "Teaching Difficult Topics with Primary Sources" November/December 2011 issue of the National Council for the Social Studies (NCSS) publication Social Education.
National Archives, Records of the Office of the Secretary of Agriculture