Adjacent counties

• Fond du Lac County – northeast
• Washington County – east
• Waukesha County – southeast
• Jefferson County – south
• Dane County – southwest
• Columbia County – west
• Green Lake County – northwest

National protected area

• Horicon National Wildlife Refuge (part)

2020 census

As of the census of 2020,^[1] the population was 89,396. The population density was 102.1 people per square mile (39.4 people/km²). There were 38,123 housing units at an average density of 43.5 units per square mile (16.8 units/km²). The racial makeup of the county was 88.8% White, 3.1% Black or African American, 0.6% Asian, 0.5% Native American, 2.4% from other races, and 4.6% from two or more races. Ethnically, the population was 6.1% Hispanic or Latino of any race.

2000 census

As of the census of 2000,^[11] there were 85,897 people, 31,417 households, and 22,313 families residing in the county. The population density was 97 people per square mile (37 people/km²). There were 33,672 housing units at an average density of 38 units per square mile (15 units/km²). The racial makeup of the county was 95.28% White, 2.49% Black or African American, 0.40% Native American, 0.34% Asian, 0.03% Pacific Islander, 0.87% from other races, and 0.58% from two or more races. 2.55% of the population were Hispanic or Latino of any race. Ancestry-wise, 56.2% were of German, 8.7% Irish, 5.0% English, 4.2% Norwegian and 3.9% selected "United States or American" ancestry. 95.4% spoke English, 2.2% Spanish and 2.0% other Indo-European languages as their language spoken at home.^[12]

There were 31,417 households, out of which 33.90% had children under the age of 18 living with them, 59.60% were married couples living together, 7.50% had a female householder with no husband present, and 29.00% were non-families. 24.10% of all households were made up of individuals, and 10.80% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 3.05.^[12]

In the county, the population was spread out, with 24.80% under the age of 18, 8.30% from 18 to 24, 31.20% from 25 to 44, 21.90% from 45 to 64, and 14.00% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 109.70 males. For every 100 females age 18 and over, there were 110.80 males.

In 2017, there were 758 births, giving a general fertility rate of 54.0 births per 1000 women aged 15–44, the 12th lowest rate out of all 72 Wisconsin counties.^[13]

Major highways

Railroads

• Amtrak
• Canadian National
• Canadian Pacific
• Union Pacific
• Wisconsin and Southern Railroad

Buses

• List of intercity bus stops in Wisconsin

Airport

• Dodge County Airport (KUNU) serves the county and surrounding communities.

Cities

Villages

Towns

Census-designated places

• Ashippun
• Burnett
• Lebanon

Unincorporated communities

Ghost town

• Clason Prairie