Milwaukee County is located in the U.S. state of Wisconsin. At the 2020 census, the population was 939,489, down from 947,735 in 2010. It is both the most populous and most densely populated county in Wisconsin, and the 45th most populous county nationwide; Milwaukee, its eponymous county seat, is also the most populous city in the state. The county was created in 1834 as part of Michigan Territory and organized the following year.

Milwaukee is the most populous city in the U.S. state of Wisconsin and the county seat of Milwaukee County. With a population of 577,222 at the 2020 census, Milwaukee is the 31st-most populous city in the United States, and the fifth-most populous city in the Midwest. It is the central city of the Milwaukee metropolitan area, the 40th-most populous metro area in the U.S. Milwaukee is categorized as a "Gamma minus" city by the Globalization and World Cities Research Network, with a regional GDP of over $102 billion in 2020.