Jefferson County is located in the state of Illinois and is part of the Mount Vernon Micropolitan Statistical Area. The county seat is Mount Vernon.

Jefferson County is governed by a seven-member Board of Commissioners. The board is elected from seven districts and serves four-year terms. The board is responsible for setting policy and overseeing the county's budget.

The county is served by the Jefferson County Sheriff's Office, which is responsible for law enforcement and corrections.

The county is home to several state parks, including Rend Lake State Fish and Wildlife Area, Pyramid State Park, and Wayne Fitzgerrell State Recreation Area.

For the most up-to-date and in-depth information, please check the public records links below.