According to theU.S. Census Bureau, the county has a total area of 380 square miles (980 km2), of which 349 square miles (900 km2) are land and 31 square miles (80 km2) (8.1%) are covered by water.[5] It is the third-smallest county in Wisconsin by total area.
As of the2020 census, the population was 19,018, with a population density of 54.4 people per square mile (21.0 people/km2). There were 10,671 housing units at an average density of 30.5 units per square mile (11.8 units/km2).[11][12]
The median age was 46.6 years, with 21.1% of residents under the age of 18 and 23.6% aged 65 years or older; for every 100 females there were 100.8 males, and for every 100 females age 18 and over there were 100.5 males age 18 and over.[12]
There were 8,099 households, of which 24.0% had children under the age of 18 living in them. Of all households, 50.4% were married-couple households, 19.8% were households with a male householder and no spouse or partner present, and 22.5% were households with a female householder and no spouse or partner present. About 30.6% of all households were made up of individuals and 15.1% had someone living alone who was 65 years of age or older. About 24.1% of housing units were vacant, with 76.3% of occupied units owner-occupied and 23.7% renter-occupied; the homeowner vacancy rate was 1.8% and the rental vacancy rate was 9.3%.[12]
27.4% of residents lived in urban areas, while 72.6% lived in rural areas.[13]
As of thecensus[14] of 2000, there were 19,105 people, 7,703 households, and 5,322 families residing in the county. Thepopulation density was 54 people per square mile (21 people/km2). There were 9,831 housing units at an average density of 28 units per square mile (11 units/km2). The racial makeup of the county was 97.81%White, 0.15%Black orAfrican American, 0.20%Native American, 0.31%Asian, 0.04%Pacific Islander, 0.89% fromother races, and 0.60% from two or more races. 2.06% of the population wereHispanic orLatino of any race. 51.8% were ofGerman, 10.6%Polish, 5.8%Irish and 5.8%American ancestry. 94.2% spokeEnglish, 3.0%Spanish and 1.8%German as their first language.
There were 7,703 households, out of which 29.40% had children under the age of 18 living with them, 58.50% weremarried couples living together, 6.90% had a female householder with no husband present, and 30.90% were non-families. 27.00% of all households were made up of individuals, and 13.80% had someone living alone who was 65 years of age or older. The average household size was 2.43 and the average family size was 2.96.
In the county, the population was spread out, with 24.20% under the age of 18, 6.60% from 18 to 24, 26.20% from 25 to 44, 24.20% from 45 to 64, and 18.80% who were 65 years of age or older. The median age was 41 years. For every 100 females there were 97.00 males. For every 100 females age 18 and over, there were 95.20 males.
In 2017, there were 380 births, giving a general fertility rate of 61.6 births per 1000 women aged 15–44, the 32nd lowest rate out of all 72 Wisconsin counties. Of these, 77 of the births occurred at home, the fourth highest for Wisconsin counties.[15] Additionally, there were 11 reported induced abortions performed on women of Green Lake County residence in 2017.[16]
In 2010, the largest religious groups by number of adherents were Catholic at 5,290 adherents, Wisconsin Synod Lutheran at 2,498 adherents, Missouri Synod Lutheran at 1,173 adherents, ELCA Lutheran at 964 adherents, and Amish at 812 adherents.[17]
Green Lake County has long been one of the most consistently Republican counties in Wisconsin. Since 1936, the county has only once voted Democratic, supportingLyndon B. Johnson in his nationwide landslide of 1964, and even then, Johnson won by just 22 votes and 0.29% in the county.
^Reported Induced Abortions in Wisconsin, Office of Health Informatics, Division of Public Health, Wisconsin Department of Health Services. Section: Trend Information, 2013-2017, Table 18, pages 17-18