This day commemorates the arrival of the first Latter-day Saint pioneers in the Salt Lake Valley (in modern day Utah, USA) in 1847.
The Church of Jesus Christ of Latter-Day Saints was founded in New York in 1830 by Joseph Smith, who received the 'word of God' and translated a book inscribed on golden plates into the Book of Mormon. The Church was growing with new members converting, but there were also enemies within the mainstream Christian churches. The Mormons built a new city on the banks of the Mississippi River but continued to be persecuted for a number of different reasons. Joseph Smith was imprisoned many times. Whilst he and his brother were in prison, it was attacked by a mob and the two Smith brothers were killed. After the murder of the founder, Mormons realized they were still not safe and the new Church leader, Brigham Young, decided they would be safer in the west of America. A mass emigration followed where they trekked along the Missouri Rivers, and then up into the Rocky Mountains to the Salt Lake Basin. The Mormons named it Zion and the river, Jordan, and began to build Salt Lake City. This part of the continent was not yet part of the United States of America and after requests from the Church, the new community was named Utah and was made a territory. Brigham Young was made governor. The Mormon community continued to grow and after some changes to their way of life, Utah was made into the 45th state of the USA in 1896.
The first commemoration of the 'new beginning' was in 1849 when Brigham Young led a procession from his home to a place called Temple Square. Religious readings took place and then there was a celebration with a thanksgiving feast. Pioneer Day is now celebrated as a birthday, an independence day, and a day of thanksgiving for Mormons. Parades, sporting events, religious readings, feasts, dances and reunions are all part of the modern-day celebrations.