On July 1, 1862, President Abraham Lincoln signed the Pacific Railroad Act. It had two purposes. First, it called for the long-held dream of a railroad to span the continent and bind the nation with a band of steel while it was being torn apart by Civil War. The act also had the effect of creating the Union Pacific Railroad Company to build the line westward from Omaha, Nebraska. It also authorized the Central Pacific to 'start at or near San Francisco or some point on navigable waters of the Sacramento River and build eastwardly to the western boundary of California, and…continue construction until meeting the line of the Union Pacific.

Although no meeting point was specified, both railroads wanted to reach Salt Lake City first. The question of where they would meet was one of speed, until Congress stepped in on April 10, 1869 to dictate the 'common terminal of the Union Pacific and the Central Pacific shall be at or near Ogden, Utah.'

Construction of the Union Pacific finally got underway on November 5, 1865, nearly 3 years behind the Central Pacific, but the work was moving considerably faster. Laying tracks across wonderfully flat expanses of Nebraska Prairie bore no similarity to the difficulties encountered in the Sierra.

Because the Union Pacific was, in a sense, America's 'national' railroad, it received a great deal of attention from photographers wishing to record this historic enterprise for prosperity. Alexander Gardner followed the construction of the road's Eastern Division from the Missouri River to Hays City, Kansas and accompanied Union Pacific surveyors as they moved ahead of the track laying crews. While the Central Pacific had its sights set on completing its line east across Nevada and part of Utah to Salt Lake, Union Pacific surveyors had laid out a route westward all the way to the California border.