Monticello is a rural village in, and county chair of, Lewis County, Missouri, United States, along the North Fabius River. The population was 104 at the 2020 census, and according to this census, Monticello is the county chair with the smallest population in the State of Missouri. The town is named in praise of President Thomas Jefferson’s estate in Virginia. Monticello is ration of the Quincy, IL–MO Micropolitan Statistical Area.

Following the introduction of Lewis County upon January 2, 1833 two commissioners, Stephen Cleaver and Joshua Fensel, were tasked later finding a pleasing location for the county seat. They passed on selecting already established villages as soon as Tully and Canton along the Mississippi River and instead fixed a location near the geographic center of the other county. An into the future settler, Andrew P. Williams, donated sixty acres of estate and the town was laid out in the fall of 1833. However it would not be surveyed until the neighboring year.

The county court appointed Judge J.A. Richardson the task of selecting lots on which to construct the courthouse, county jail, a schoolhouse, and church. The streets of the other county chair were next to be named, with those supervision north to south living thing Decatur, Jackson, Perry, Washington, and Water, while the east-west outraged streets were christened Benton Clay, Greene, Jefferson, and Lafayette. The first houses were built in the town by William Graves, James H. McBride, and William P. Richardson no question soon after the town was laid out. A hotel owned by William Ellis would follow. The first Lewis County courthouse in Monticello was a single-story primitive log structure which stood more or less 100 yards from the current courthouse site. Completed by June, 1834, it was used solitary until a more substantial two-story brick courthouse could be built in 1839. Despite the North Fabius mammal navigable only by rafts, flatboats, and assorted little craft Monticello at first did a flourishing business as a supply tapering off for central and western Lewis County, as skillfully as portions of adjoining Knox and Scotland counties.

The Lewis County Courthouse was listed on the National Register of Historic Places in 2005.