Monticello /mɒntɪˈsɛloʊ/ is a city located in San Juan County, Utah, and is the county seat. It is the second most populous city in San Juan County, with a population of 1,958 at the 2000 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.Monticello, along with much of San Juan County, experienced an increase in population and economic activity during the uranium boom from the late 1940s to the early 1960s. Several uranium and vanadium mines were opened in the area, and a uranium processing mill was operated in Monticello by the Federal Government from 1948 to 1960. Following the uranium boom, a massive cleanup project was conducted by the U.S. Department of Energy from 1989 to 2004 to remove radioactive material from lands and buildings and to restore the land formerly occupied by the mill.