Construction Finished With a Single Word: "Done"

As the two companies approached the Promontory Mountains in Utah, both realized there was only one route through. Blasting began on both sides to lay track. The east slope was more difficult as the grade was steeper. On both sides, fills and trestles were necessary for crossing deep ravines. Finally on April 9, the Union Pacific, and on April 11, the Central Pacific, stopped trying to lay tracks ahead. Congress established that they would meet at Promontory Summit.

By April 16, 1869 the two crews were only 50 miles apart. The Union Pacific crew was delayed because it ran out of ties. They also had to build three more trestles to make the summit.
May 8 was the target date for the union of the two railroads. On May 7, the two lines were just 2,500 feet apart. Former California Governor Leland Stanford traveled to Utah along with other officials from California and Nevada, bringing two golden spikes with him. One was made by David Hewes, one of the Central Pacific's largest supply contractors. The other was sent by The San Francisco "News Letter." West Evans, the contractor who supplied most of the Central Pacific ties, hand-polished and waxed a special last tie made out of laurelwood. The Pacific Union Express Company sent a silver plated sledge for the final blow.
The Union Pacific team was not prepared by May 8. Many of the dignitaries traveling on their end got held up by weather or by labor disputes. However, on May 9 the Union Pacific laid the final 2,500 feet of track, leaving one length of rail separation. The two trains from the east arrived the morning of May 10th.
At noon on May 10, 1869 a ceremony began with approximately 600 people in attendance. The two engines, the Central Pacific's Jupiter and the Union Pacific's No. 119, stood cowcatcher to cowcatcher at each end of the last rail.
At 12:20 p.m., one official from each railroad joined together to lay in the ceremonial last tie using the gold spikes. The silver sledgehammer was used to "drive" the spikes, but not enough to damage them. (The real final tie, spike and sledge were ordinary.) The two trains were then driven together, and a bottle of champagne was broken over the laurel tie. A telegraph went out across the nation with the simple message: "Done." The transcontinental railroad was complete. At that instant in Promontory Point, Utah, coast-to-coast travel time was reduced from four to six months to six days. In just seven years, the Union Pacific railroad had built 1,086 miles of railroad lines from Omaha, Nebraska. The Central Pacific had built 690 miles from Sacramento, California. Both railroads had crossed a major mountain range, the Rocky Mountains in the East and the Sierra Nevada in the west.
While the Transcontintental Railroad was started in the midst of a war that divided America, its completion marked a new unity and connection between the east and west coasts that further defined the United States as a single nation. The railroad signaled the death knell for the "western frontier" as it made possible the large-scale immigration to, agricultural and other trade with, and ultimately the industrialization of the western U.S.