Jefferson County is a county located in the U.S. state of Wisconsin. As of 2000, the population was 74,021. Its county seat is Jefferson. The county is believed named for Jefferson County, NY. The county is in the Watertown-Fort Atkinson metro area.The estimated population in 2004 was 78,497. This was an increase of 6.05% from the 2000 census.
Learn more about this county.County of Jefferson, WI Chamber of CommerceCounty of Jefferson, WI newspaperCounty of Jefferson, WI official siteState of Wisconsin official site