The first white man to have a dwelling in Monticello may have been a cattleman named Patrick O'Donall in 1879. In 1887 Mormon pioneers from Bluff a little town in the surrounding area were sent to establish a new settlement. In 1888 a meeting was held suggesting three names,none of the names were chosen then President Francis A. Hammond the leading Mormon (Church of Jesus Christ of Latter Day Saints) sake President leader suggested Monticello in honor of Thomas Jefferson and the name was approved.
Along with much of San Juan County Monticello increased in economic growth and population because the uranium boom in the latter part of 1940's to early 1960's. After the boom there was a massive cleanup by the U.S. Department of Energy going from 1989 to 2004 putting the land back as it was before the boom.
In the US Census in 2000 the population was 1,958.
Monticello is is the county seat, in 2000 Federal Cenus the populatation was 1,958. You may obtain records for San Juan County records by writing to County Courthouse 117 South Main Monticello 84535.