The First Transcontinental Railroad (known originally as the "Pacific Railroad" and later as the "Overland Route") was a 1,907-mile (3,069 km) contiguous railroad line constructed between 1863 and 1869 across the western United States to connect the Pacific coast at San Francisco Bay. Opened for through traffic on May 10, 1869 with the ceremonial driving of the "Last Spike" (later often called the "Golden Spike") with a silver hammer at Promontory Summit, Utah.