San Juan County, Utah: History
The Utah Territory authorized the creation of San Juan County on February 17, 1880, with territories annexed from Iron, Kane, and Piute counties. There has been no change in its boundaries since its creation. Monticello was founded in 1887, and by 1895 it was large enough to be designated the seat of San Juan County. On September 13, 2025, two extreme-level tornadoes touched down in the county. One was an EFU, the other was a strong EF2.