When the first white settlers arrived in the 1830s, the Mequon area was inhabited by the Menominee, Potawatomi, and Sauk people. In the 1840s, German immigrants settled in the community, building farms and hydropowered mills along the Milwaukee River. Much of the community remained rural, while Thiensville developed as a market town along the local railway, providing services to the farmers. Thiensville incorporated as a village in 1910. Mequon remained rural in the early 20th century but experienced significant population growth during the suburbanization that followed World War II. The community incorporated as a city in 1957 to avoid annexation by the City of Milwaukee. The City of Mequon completely surrounds Thiensville, leading some residents to call Thiensville "Mequon's donut hole." The two municipalities have a close relationship, with a shared chamber of commerce, library, and school district.