According to the U.S. Census Bureau, the county has an area of 1,576 square miles (4,080km2), of which 1,545 square miles (4,000km2) is land and 31 square miles (80km2) (2.0%) is water. It is Wisconsin's largest county by land area and fourth-largest by total area.
Marker at the 45×90 point near Rietbrock
The Marathon County Park Commission has posted a geographical marker that identifies the spot (45°N, 90°W) of the exact center of the northern half of the Western Hemisphere, meaning that it is a quarter of the way around the world from the Prime Meridian and halfway from the Equator to the North Pole.
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010 2020
Racial and ethnic composition
Marathon County, Wisconsin – Racial and ethnic composition Note: the US Census treats Hispanic/Latino as an ethnic category. This table excludes Latinos from the racial categories and assigns them to a separate category. Hispanics/Latinos may be of any race.
As of the 2020 census, the county had a population of 138,013. The population density was 89.3 peopleper square mile (34.5 people/km2). There were 59,828 housing units at an average density of 38.7 unitsper square mile (14.9 units/km2).
The median age was 41.1 years, 22.6% of residents were under the age of 18, and 18.5% of residents were 65 years of age or older. For every 100 females there were 101.4 males, and for every 100 females age 18 and over there were 99.9 males age 18 and over.
There were 56,517 households in the county, of which 27.4% had children under the age of 18 living in them. Of all households, 51.4% were married-couple households, 18.8% were households with a male householder and no spouse or partner present, and 21.7% were households with a female householder and no spouse or partner present. About 28.5% of all households were made up of individuals, and 11.6% had someone living alone who was 65 years of age or older.
Of the 59,828 housing units, 5.5% were vacant. Among occupied housing units, 72.1% were owner-occupied and 27.9% were renter-occupied. The homeowner vacancy rate was 1.0% and the rental vacancy rate was 6.3%.
56.6% of residents lived in urban areas, while 43.4% lived in rural areas.
2000 Census Age Pyramid for Marathon County
2000 census
As of the census of 2000, there were 125,834 people, 47,702 households, and 33,868 families residing in the county. The population density was 81 peopleper square mile (31 people/km2). There were 50,360 housing units at an average density of 33 unitsper square mile (13 units/km2). The racial makeup of the county was 93.84% White, 0.28% Black or African American, 0.35% Native American, 4.54% Asian, 0.02% Pacific Islander, 0.26% from other races, and 0.72% from two or more races. 0.78% of the population were Hispanic or Latino of any race. 52.6% were of German and 13.6% Polish ancestry. 92.9% spoke English, 3.4% Hmong, 1.1% German and 1.1% Spanish as their first language.
There were 47,702 households, out of which 34.00% had children under the age of 18 living with them, 59.90% were married couples living together, 7.40% had a female householder with no husband present, and 29.00% were non-families. 23.60% of all households were made up of individuals, and 9.50% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.11.
In the county, the population was spread out, with 26.80% under the age of 18, 8.20% from 18 to 24, 29.50% from 25 to 44, 22.50% from 45 to 64, and 13.00% who were 65 years of age or older. The median age was 36 years. For every 100 females, there were 99.50 males. For every 100 females aged 18 and over, there were 97.40 males.
Libraries
The Marathon County Public Library (MCPL) is headquartered in downtown Wausau. There are eight branch libraries, in Athens, Edgar, Hatley, Marathon City, Mosinee, Rothschild, Spencer, and Stratford.
At founding, Marathon was reliably Democratic, attributed to its large population of German Catholic immigrants, who had many grievances against the Republican Party. In 1896, the Democratic Party's adoption of the populist movement infuriated the local anti-free silver Germans, and Marathon broke for the Republican Party for the first time since formation. Deeply progressive, the county saw the Democratic Party's perceived abandonment of progressive values as an offense, and like the state became a Republican stronghold for the next four election cycles. Marathon's semi-urban but largely rural and heavily German Catholic population, which reflected the demographics of the state, led to it eventually becoming one of the most reliable bellwether counties in the state, voting for the candidate that won the state in every election between 1892 and 1996 (with two exceptions: 1928, when the losing candidate was a Catholic, and 1940, when many German Americans turned sharply away from Franklin D. Roosevelt, who was seen as Anglophilic). Starting in 2000, Marathon County began following the trend of many other rural counties, breaking for George W. Bush even as Wisconsin remained a safely blue state and continuing to shift rightward (with the exception of Barack Obama's 2008 landslide). Since 2008, Republicans have gained ground in the county in every election cycle even as the state has flip-flopped between Republicans and Democrats. Marathon County's Republican swing has continued locally as well - it has not voted for a Democrat at the state level since 2006, and Republicans won the mayoralty of Wausau in 2024.
United States
Wisconsin
