Pioneer Day is an official holiday celebrated on July 24 in the U.S. state of Utah, with some celebrations in regions of surrounding states originally settled by Mormon pioneers. It commemorates the entry of Brigham Young and the first group of Mormon pioneers into the Salt Lake Valley on July 24, 1847, where the Latter-day Saints settled after being forced from Nauvoo, Illinois, and other locations in the eastern United States. Parades, fireworks, rodeos, and other festivities help commemorate the event. Similar to July 4, most governmental offices and many businesses are closed on Pioneer Day.

In addition to being an official holiday in Utah, Pioneer Day is considered a special occasion by many members of The Church of Jesus Christ of Latter-day Saints (LDS Church). On Pioneer Day, some Latter-day Saints walk portions of the Mormon Trail or reenact entering the Salt Lake Valley by handcart. Latter-day Saints throughout the United States and around the world may celebrate July 24 in remembrance of the LDS Church's pioneer era, with songs, dances, potlucks, and pioneer related activities.

While the holiday has strong links to the LDS Church, it is a celebration of everyone, regardless of faith and nationality, who emigrated to the Salt Lake Valley during the pioneer era, which is generally considered to have ended with the 1869 arrival of the transcontinental railroad.

en.wikipedia.org/wiki/Pioneer_Day_(Utah)