It was named for Thomas Jefferson, principal draftsman of the Northwest Ordinance and President of the United States from 1801 through 1809.

The county fell into economic decline after the American Civil War, as industry began to shift from southern Indiana to the northern part of the state.

The fire forced the evacuation of the nearby county jail, and effectively shut down the downtown area of the city.

[5] It was later determined the fire was accidentally started by workers who were welding on the metal roof dome.

The tallest waterfall in Indiana, Fremont Falls, is located in Hanover.

[6] Jefferson County makes up the Madison, IN Micropolitan Statistical Area.

The commissioners are charged with executing the acts legislated by the council, collecting revenue, and managing the day-to-day functions of the county government.

The judge on the court is elected to a term of four years and must be a member of the Indiana Bar Association.

[12] Jefferson County is part of Indiana's 6th congressional district and is represented in Congress by Republican Luke Messer.

[14] As of the 2010 United States Census, there were 32,428 people, 12,635 households, and 8,456 families residing in the county.