Monticello (/ˌmɒntɪˈsɛloʊ/ (ⓘ) MON-tih-SEL-oh) 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 1,824 at the 2020 census. It was made a city in 1910.