Washington County was created on December 7, 1836, by theWisconsin Territory Legislature, withPort Washington designated as the county seat. It was run administratively fromMilwaukee County until 1840, when an Act of Organization allowed the county self-governance, and the county seat was moved toGrafton, then called Hamburg. This solution was not satisfactory, as at that time four cities were vying to become the county seat: Port Washington, Grafton,Cedarburg, andWest Bend. At least four inconclusive elections were held between 1848 and 1852, but the results were unusable due to accusations of foul play and serious irregularities.
In 1852, the state Legislature attempted to split the county into a northern and southern half, with the northern half retaining the name and the southern half becoming Tuskola County. Voters refused this decision, so in 1853 the Legislature again split the county, this time into a western and eastern portion. The western portion remained Washington County, with West Bend as its county seat, while the eastern portion becameOzaukee County, with Port Washington as its county seat.[5]
According to theU.S. Census Bureau, the county has a total area of 436 square miles (1,130 km2), of which 431 square miles (1,120 km2) is land and 5.0 square miles (13 km2) (1.2%) is water.[6] It is the fifth-smallest county in Wisconsin by total area.
Washington County was formerly served by theWashington County Commuter Express until 2023 when the county board elected to terminate the service without replacement, as of the end of 2023 there are no public transit options linking Washington County to the rest of the Milwaukee Metro area. Limited county sponsored shared ride taxi service remains available.
Erin Aero Airport also exists as a small airstrip in the Town of Erin. Some maps claim the existence Arrowhead Springs, Doering Farms Airfield, Hahn Sky Ranch, and Willow Creek Airports, but these do not exist.
As of thecensus of 2020,[1] the population was 136,761. Thepopulation density was 317.6 people per square mile (122.6 people/km2). There were 58,311 housing units at an average density of 135.4 units per square mile (52.3 units/km2). The racial makeup of the county was 91.7%White, 1.4%Asian, 1.3%Black orAfrican American, 0.3%Native American, 1.1% fromother races, and 4.2% from two or more races. Ethnically, the population was 3.5%Hispanic orLatino of any race.
As of thecensus[13] of 2000, there were 117,493 people, 43,842 households, and 32,749 families residing in the county. Thepopulation density was 273 people per square mile (105 people/km2). There were 45,808 housing units at an average density of 106 units per square mile (41 units/km2). The racial makeup of the county was 97.69%White, 0.40%Black orAfrican American, 0.25%Native American, 0.57%Asian, 0.03%Pacific Islander, 0.40% fromother races, and 0.66% from two or more races. 1.30% of the population wereHispanic orLatino of any race. 59.9% were ofGerman, 6.3%Polish and 5.5%Irish ancestry. 95.5% spokeEnglish, 2.0%German and 1.7%Spanish as their first language.
There were 43,842 households, out of which 36.40% had children under the age of 18 living with them, 64.20% weremarried couples living together, 7.20% had a female householder with no husband present, and 25.30% were non-families. 20.30% of all households were made up of individuals, and 7.60% had someone living alone who was 65 years of age or older. The average household size was 2.65 and the average family size was 3.08.
In the county, the population was spread out, with 26.70% under the age of 18, 7.20% from 18 to 24, 31.50% from 25 to 44, 23.40% from 45 to 64, and 11.20% who were 65 years of age or older. The median age was 37 years. For every 100 females there were 99.50 males. For every 100 females age 18 and over, there were 97.00 males.
The East High School and West High Schools share the same building but are separated.
The Slinger High School's Owls and the Hartford Union High School's Orioles have a rivalry, playing every year at the Coaches vs Cancer Game. Despite their rivalry they have a joint swim team based out of Hartford.
All high schools in the county feed into the West Bend Ice Bears for boys hockey.
East, Germantown, Hartford Union, Slinger, and West High Schools feed into the Cedarburg co-op for girls hockey, called the Lakeshore Lightning.
East, Slinger, and West High Schools feed into the West Bend Rush for boys and girls lacrosse.
A portion of Cedarburg School District reaches into Washington County.
The County Executive is Josh Schoemann, a Republican who is the 1st County Executive, with the office having been established in 2020. Schoemann served as County Administrator from 2014 until 2020. In 2020, the position of County Executive was established to replace the Administrator role. While the responsibilities of the two positions are functionally identical, the primary distinction lies in the method of selection: the County Executive is an elected official, whereas the County Administrator was appointed.
Like most other suburban counties surrounding Milwaukee (the "WOW counties"), Washington County is aRepublican stronghold. Since1940, the county has been won by the Republican presidential candidate in every election except 1964, as is the case in neighboring Ozaukee and Waukesha counties. Additionally,John F. Kennedy,Lyndon Johnson andJimmy Carter are the only Democratic presidential candidates since the1936 election to have crossed the 40 percent mark. In 2008, whileBarack Obama won Wisconsin by 14 points, Washington County, one of the 13 out of 72 counties to vote for his Republican rivalJohn McCain was his weakest county in the state, as McCain won it by almost 30 points; and other WOW counties were the only three counties where Obama did not win 40 percent of the vote.[15]