Utah has a fascinating history from the days before it was a United States territory to today. The first Europeans arrived in the area in 1765. In 1821, Mexico won its independence from Spain and claimed Utah for itself. In 1832, Antoine Robidoux built the first trading post in Utah, and in 1841, John Bartleson led the first wagon train across Utah to California. During the 1800s, Utah bore the indicia of western expansion. Many regard the completion of the transcontinental railroad at Promontory Summit, Utah, on May 10, 1869 as not only one of the most important historical events in Utah, but also one of the most momentous in U.S. history. Utah stands unique in its history and traditions, and it cannot be understood apart from the influence of Church of Jesus Christ of Latter-Day Saints (the “LDS church”) and its adherents, the Mormons. Utah’s path to statehood began principally because of precipitous settlement by Mormons, who moved west after failed settlement attempts in New York, Illinois, and, most notably, in Jackson County, Missouri, where they had intended to establish an everlasting temple. In 1847, Brigham Young, by then the leader of the main branch of the LDS church, entered the Salt Lake Valley with 148 comrades and founded Salt Lake City. At the time, the area was part of Mexico, but early in 1848 through the Treaty of Guadalupe Hidalgo, Mexico ceded 525,000 square miles, including present-day Utah, to the United States.