Winnebago County is a county in the U.S. state of Wisconsin. As of the 2020 census, the population was 171,730. Its county seat is Oshkosh. It was named for the historic Winnebago people, a federally recognized Native American tribe now known as the Ho-Chunk Nation. Chief Oshkosh was a Menominee leader in the area. Winnebago County comprises the Oshkosh-Neenah, WI Metropolitan Statistical Area, which is included in the Appleton-Oshkosh-Neenah, WI Combined Statistical Area.

The region was occupied by several Native American tribes in the period of European encounter, including the Sauk, Fox, Menominee, and Ojibwa (known as Chippewa in the US). French traders from what is now Canada had early interaction with them, as did French Jesuit missionaries, who sought to convert them to Catholicism. European and American settlement encroached on their traditional territories, and the United States negotiated treaties in the mid-19th century to keep pushing the Indians to the west.

Winnebago County was created in 1840 by European Americans and organized in 1848. The name Winnebago is of Algonquin origin, with variations used by the Fox and Potowatomi to refer to the Fox River below Lake Winnebago, which sometimes got muddy and full of fish. It means 'people dwelling by the fetid or ill-smelling water', which may also refer to a sulfur spring. The county seat, Oshkosh, was incorporated as a city in 1853, when it already had a population of nearly 2,800.

Chief Oshkosh was the namesake for the county seat. A leader of the Menominee in the region, he was successful in gaining authorization from the federal government for 2500 of his people to remain in Wisconsin, at a time when the government was pushing for their removal west of the Mississippi River.

According to the U.S. Census Bureau, the county has a total area of 579 square miles (1,500 km), of which 434 square miles (1,120 km) is land and 144 square miles (370 km) (25%) is water.

• Waupaca County - northwest
• Outagamie County - northeast
• Calumet County - east
• Fond du Lac County - south
• Green Lake County - southwest
• Waushara County - west

• Canadian National
• Wisconsin and Southern Railroad

• GO Transit (Wisconsin)
• Valley Transit (Wisconsin)

Wittman Regional Airport (KOSH) serves the county and surrounding communities.

Brennand Airport (79C) in the Town of Clayton is a major recreational aircraft hub year-round.

Commercial airline service for Winnebago County is provided by Appleton International Airport in the neighboring Outagamie County.

Historical population

Census	Pop.	Note	%±
1840	135		—
1850	10,167		7,431.1%
1860	23,770		133.8%
1870	37,279		56.8%
1880	42,740		14.6%
1890	50,097		17.2%
1900	58,225		16.2%
1910	62,116		6.7%
1920	63,897		2.9%
1930	76,622		19.9%
1940	80,507		5.1%
1950	91,103		13.2%
1960	107,928		18.5%
1970	129,931		20.4%
1980	131,703		1.4%
1990	140,320		6.5%
2000	156,763		11.7%
2010	166,994		6.5%
2020	171,730		2.8%
U.S. Decennial Census 1790–1960 1900–1990 1990–2000 2010–2020

As of the census of 2020, the population was 171,730. The population density was 395.1 people per square mile (152.5 people/km). There were 76,046 housing units at an average density of 174.9 units per square mile (67.5 units/km). The racial makeup of the county was 86.2% White, 3.3% Asian, 3.0% Black or African American, 0.7% Native American, 1.8% from other races, and 5.1% from two or more races. Ethnically, the population was 4.8% Hispanic or Latino of any race.

As of the census of 2000, there were 156,763 people, 61,157 households, and 39,568 families residing in the county. The population density was 357 people per square mile (138 people/km). There were 64,721 housing units at an average density of 148 units per square mile (57 units/km). The racial makeup of the county was 94.92% White, 1.12% Black or African American, 0.46% Native American, 1.84% Asian, 0.02% Pacific Islander, 0.72% from other races, and 0.92% from two or more races. 1.96% of the population were Hispanic or Latino of any race. 52.4% were of German, 6.2% Irish and 5.7% Polish ancestry. 94.6% spoke English, 2.5% Spanish and 1.0% Hmong as their first language.

There were 61,157 households, out of which 31.00% had children under the age of 18 living with them, 53.00% were married couples living together, 8.30% had a female householder with no husband present, and 35.30% were non-families. 27.60% of all households were made up of individuals, and 9.90% 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 2.99.

By age, 23.80% of the population was under 18, 11.80% from 18 to 24, 30.40% from 25 to 44, 21.50% from 45 to 64, and 12.50% were 65 or older. The median age was 35 years. For every 100 females there were 99.40 males. For every 100 females age 18 and over, there were 97.80 males.

In 2017, there were 1,833 births, giving a general fertility rate of 56.5 births per 1000 women aged 15–44, the 15th lowest rate out of all 72 Wisconsin counties. Additionally, there were 123 reported induced abortions performed on women of Winnebago County residence in 2017.

Winnebago County is governed by the 36-member Winnebago County Board of Supervisors. Supervisors are elected to the board in a nonpartisan election held the first Tuesday of April in even numbered years and serve two-year terms. The board has several committees. It meets on the third Tuesday of each month at the Winnebago County Courthouse in Oshkosh.

United States presidential election results for Winnebago County, Wisconsin

Year	Republican		Democratic		Third party(ies)
	No.	%	No.	%	No.	%
2024	49,179	51.57%	44,660	46.83%	1,532	1.61%
2020	47,796	50.83%	44,060	46.86%	2,176	2.31%
2016	43,445	49.86%	37,047	42.52%	6,643	7.62%
2012	42,122	47.24%	45,449	50.97%	1,602	1.80%
2008	37,946	43.28%	48,167	54.94%	1,564	1.78%
2004	46,542	52.53%	40,943	46.21%	1,111	1.25%
2000	38,330	50.38%	33,983	44.67%	3,767	4.95%
1996	27,880	42.73%	29,564	45.31%	7,803	11.96%
1992	33,709	43.56%	27,234	35.19%	16,443	21.25%
1988	35,085	54.82%	28,508	44.54%	410	0.64%
1984	39,014	62.74%	22,791	36.65%	378	0.61%
1980	34,286	53.28%	24,203	37.61%	5,864	9.11%
1976	32,149	55.35%	24,485	42.16%	1,448	2.49%
1972	29,488	57.28%	20,450	39.72%	1,544	3.00%
1968	25,361	53.84%	18,605	39.50%	3,138	6.66%
1964	21,084	47.03%	23,636	52.72%	115	0.26%
1960	28,598	61.72%	17,656	38.11%	80	0.17%
1956	28,759	71.44%	11,115	27.61%	380	0.94%
1952	28,172	68.17%	13,016	31.49%	140	0.34%
1948	17,165	55.18%	13,116	42.16%	829	2.66%
1944	19,310	59.56%	12,841	39.61%	269	0.83%
1940	18,697	54.14%	15,570	45.08%	268	0.78%
1936	11,679	36.93%	18,522	58.57%	1,420	4.49%
1932	11,505	41.31%	15,591	55.98%	756	2.71%
1928	16,191	61.10%	9,995	37.72%	315	1.19%
1924	11,239	48.70%	1,801	7.80%	10,038	43.50%
1920	12,035	69.53%	3,397	19.63%	1,876	10.84%
1916	5,923	50.49%	5,242	44.69%	566	4.82%
1912	1,922	17.01%	4,631	41.00%	4,743	41.99%
1908	6,797	52.24%	5,511	42.36%	703	5.40%
1904	7,720	62.63%	4,006	32.50%	600	4.87%
1900	7,467	55.67%	5,605	41.78%	342	2.55%
1896	7,898	59.23%	5,089	38.17%	347	2.60%
1892	5,354	45.06%	5,893	49.60%	635	5.34%

Winnebago County has become a swing county in recent decades. It has voted for the winning presidential candidate in every election since 1980, except in 1992 when it supported George Bush, and in 2020, when it supported Donald Trump.

• Appleton (mostly in Outagamie County and Calumet County)
• Menasha (partly in Calumet County)
• Neenah
• Omro
• Oshkosh (county seat)

• Fox Crossing
• Winneconne

• Butte des Morts
• Eureka
• Waukau
• Winchester

• Delhi
• Menasha (former)

• Martin Madison (born 1854, Winnebago County), South Dakota politician

• National Register of Historic Places listings in Winnebago County, Wisconsin

• Commemorative Biographical Record of the Fox River Valley Counties of Brown, Outagamie and Winnebago. Chicago: J. H. Beers, 1895.
• Lawson, Publius V. (ed.) History, Winnebago County, Wisconsin: Its Cities, Towns, Resources, People. Chicago: C. F. Cooper, 1908.

• Winnebago County official website
• Winnebago County map from the Wisconsin Department of Transportation

44°04′N 88°38′W / 44.06°N 88.64°W / 44.06; -88.64