Nason is a city in Jefferson County, Illinois, United States. The population was 199 people as of the 2020 census, making it the least populous incorporated city in the state of Illinois. It is part of the Mount Vernon Micropolitan Statistical Area.
Geography
Nason is located in southern Jefferson County south of Mount Vernon, the county seat. It sits between the two northern arms of Rend Lake, a reservoir on the Big Muddy River.
According to the 2021 census gazetteer files, Nason has a total area of , all land.
Demographics
As of the 2020 census