Jefferson County, Wisconsin Information
|Jefferson County, Wisconsin|
Jefferson County courthouse
Location within the U.S. state of Wisconsin
Wisconsin's location within the U.S.
|Named for||Jefferson County, New York|
|• Total||583 sq mi (1,510 km2)|
|• Land||556 sq mi (1,440 km2)|
|• Water||26 sq mi (67 km2), 4.5%|
|• ( 2010)||83,686|
|• Density||150/sq mi (60/km2)|
|Time zone||Central: UTC−6/ −5|
Jefferson County was created in 1836 as part of Wisconsin Territory and was organized in 1839.  Jefferson County was founded by "Yankee" settlers from New England.  It was named after Jefferson County, New York, where some of the original settlers came from.  The town of Watertown, Wisconsin was named after Watertown, New York in Jefferson County, New York.
- Watertown Municipal Airport (KRYV) provides services for the county and surrounding communities.
- Fort Atkinson Municipal Airport (61C), enhances county service.
- Dodge County - north
- Waukesha County - east
- Walworth County - southeast
- Rock County - southwest
- Dane County - west
|U.S. Decennial Census
1790–1960  1900–1990 
1990–2000  2010–2014 
As of the census  of 2010, there were 83,686 people, 32,117 households, and 21,872 families residing in the county. The population density was 133 people per square mile (51/km²). There were 30,092 housing units at an average density of 54 per square mile (21/km²). The county's racial makeup was 96.34% White, 0.28% Black or African American, 0.34% Native American, 0.45% Asian, 0.02% Pacific Islander, 1.65% from other races, and 0.93% from two or more races. 4.09% of the population were Hispanic or Latino of any race. 55.1% were of German, 6.1% Norwegian, 6.0% Irish and 5.1% American ancestry according to Census 2000.
There were 28,205 households out of which 33.20% had children under the age of 18 living with them, 58.50% were married couples living together, 8.20% had a female householder with no husband present, and 29.50% were non-families. 23.60% of all households were made up of individuals and 9.60% had someone living alone who was 65 years of age or older. The average household size was 2.55 and the average family size was 3.02.
In the county, the population was spread out with 25.20% under the age of 18, 8.50% from 18 to 24, 30.40% from 25 to 44, 23.20% from 45 to 64, and 12.60% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 98.40 males. For every 100 females age 18 and over, there were 96.80 males.
In 2017, there were 861 births, giving a general fertility rate of 53.7 births per 1000 women aged 15–44, the eleventh lowest rate out of all 72 Wisconsin counties. 
The County Board of Supervisors, with 30 members, serves as the legislative body for the county. There are seven elected officials in addition to the County Board of Supervisors. County-wide partisan elections are held in November. The County Board's members are elected for two-year terms during a spring non-partisan election. The County Board is responsible for the county administrator.[ clarification needed] The County Board elects a chairman, vice-chairman, and second vice-chairman.
Jefferson County has been primarily Republican since 1940. Only three Democratic presidential candidates have won the county since then in 1964, 1996, & 2008. Lyndon B. Johnson in 1964 is the last Democratic Party candidate to win a majority of the county's votes.
- Fort Atkinson
- Jefferson (county seat)
- Lake Mills
- Watertown (partly in Dodge County)
- Whitewater (mostly in Walworth County)
- Cambridge (mostly in Dane County)
- Johnson Creek
- Lac La Belle (mostly in Waukesha County)
- Blackhawk Island
- Cold Spring
- Glenn Oaks Beach
- Heath Mills
- Hoopers Mill
- Jefferson Junction
- Koshkonong (partial)
- Koshkonong Manor
- Koshkonong Mounds
- Lake Lac La Belle
- London (partial)
- North Shore
- Portland (partial)
- Sylvan Mounds
- Vinnie Ha Ha
- "State & County QuickFacts". United States Census Bureau. Archived from the original on June 6, 2011. Retrieved January 21, 2014.
- "Find a County". National Association of Counties. Archived from the original on 2011-05-31. Retrieved 2011-06-07.
- "Wisconsin: Individual County Chronologies". Wisconsin Atlas of Historical County Boundaries. The Newberry Library. 2007. Retrieved August 14, 2015.
- " Term: Jefferson County [origin of place name]" in Dictionary of Wisconsin History.
- "2010 Census Gazetteer Files". United States Census Bureau. August 22, 2012. Retrieved August 5, 2015.
- "Population and Housing Unit Estimates". Retrieved June 9, 2017.
- "U.S. Decennial Census". United States Census Bureau. Archived from the original on April 26, 2015. Retrieved August 5, 2015.
- "Historical Census Browser". University of Virginia Library. Retrieved August 5, 2015.
- Forstall, Richard L., ed. (March 27, 1995). "Population of Counties by Decennial Census: 1900 to 1990". United States Census Bureau. Retrieved August 5, 2015.
- "Census 2000 PHC-T-4. Ranking Tables for Counties: 1990 and 2000" (PDF). United States Census Bureau. April 2, 2001. Retrieved August 5, 2015.
- "American FactFinder". United States Census Bureau. Retrieved 2011-05-14.
- Annual Wisconsin Birth and Infant Mortality Report, 2017 P-01161-19 (June 2019): Detailed Tables
- "Jefferson County Library Service". Retrieved 24 April 2012.
- "Wisconsin Public Library Service Data, 2010" (PDF). Department of Public Instruction. Archived from the original (PDF) on 2012-03-06.
- Leip, David. "Dave Leip's Atlas of U.S. Presidential Elections". uselectionatlas.org. Retrieved 8 April 2018.
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