Jefferson County, Illinois
County: Jefferson County
Lat/Long: 38.3000, -88.9333
The Illinois General Assembly created Jefferson County in 1819, out of parts of Edwards and White counties. Later that year, commissioners appointed for the purpose located the site of the new county's seat and the county commissioners' court named the new town Mt. Vernon.
"An Act Forming a Separate County out of Edwards and White Counties," 26 March 1819, Laws of Illinois (1819), 267-68; William H. Perrin, ed., History of Jefferson County, Illinois (Chicago: Globe, 1883), 136, 281-83.