High Quality Content by WIKIPEDIA articles! Pioneer Day (also archaically called the Day of Deliverance) 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.