Massac County is located in the southernmost part of Illinois, and is part of the Paducah, KY-IL Micropolitan Statistical Area. The county seat is Metropolis.

Massac County was formed in 1843 out of parts of Johnson and Pope counties.

The county government is composed of a Board of Commissioners, which is the legislative body, and a County Executive, who is the administrative head. The County Executive is elected by the voters of the county and is responsible for the day-to-day operations of the county government. The Board of Commissioners is composed of seven members, each elected from a single-member district.

The county is served by a State's Attorney's Office, which is responsible for prosecuting criminal cases in the county. The State's Attorney is elected by the voters of the county.

The county is also served by a Coroner's Office, which is responsible for investigating deaths in the county. The Coroner is elected by the voters of the county.

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