Monticello is a city located in San Juan County, Utah, United States and is the county seat. It is the second most populous city in San Juan County, with a population of 1,972 at the 2010 census. The Monticello area was settled in July 1887 by pioneers from the Church of Jesus Christ of Latter-day Saints. Monticello, named in honor of Thomas Jefferson's estate, became the county seat in 1895 and was incorporated as a city in 1910.