Nason is a city in Jefferson County, Illinois, United States. The population was 236 people as of the 2010 census, making it the least populous incorporated city in the state of Illinois. It is part of the Mount Vernon Micropolitan Statistical Area.
nason is a city in jefferson county illinois united states the population was 236 people as of the 2010 census making it the least populous incorporated city in the state of illinois it is part of the mount vernon micropolitan statistical area