Historians agree that the driving of the golden spike marking the completion of the transcontinental railroad at Promontory Summit, Utah, on 10 May 1869 was one of the most important events in United States history, as it was also in Utah history. In fact, 1869 is considered to be a benchmark year in Utah history--the pioneer era coming to an end with the coming of the railroad.

Brigham Young, as community leader and president of the Church of Jesus Christ of Latter-day Saints, foresaw the impact that the coming of the railroad would have and wanted the transcontinental rail line built through Salt Lake City. He was aware of the role that a railroad could play in tying a community together as well as connecting a region with the outside world. After representatives of both the Central Pacific and the Union Pacific met with him and explained the difficulty and extra expense of a route through Salt Lake City, Young accepted the decision and helped wherever he could to speed the completion of the project, including arranging for the use of local contractors for the construction of the tracks across the territory.

The construction of a connecting railroad line south to Salt Lake City, and later into almost all parts of the state, had a much larger impact on the local populace than did the joining of the rails at Promontory. In early 1869, prior to the completion of the transcontinental railroad, Mormon Church leaders began working on the organization of a connecting railroad between Ogden and Salt Lake City. In January 1870 that line was completed, connecting Salt Lake City to the national rail system. One of the benefits that the Mormon Church received from the coming of the railroad was the availability of low-cost transportation that would help to bring large numbers of its members to the new Zion. From places as distant as Europe, new members came by way of the ports of call along the East and Gulf coasts.

The Union Pacific was the first of the major railroad companies to successfully build within Utah's borders, connecting with the Central Pacific tracks at Promontory in 1869. Twenty years later, Union Pacific had become the largest railroad company in the territory. In 1889 the Union Pacific consolidated the control of its interests in Utah and Idaho through the organization of the Oregon Short Line and Utah Northern Railway.