Wisconsin ( (listen)) is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake Michigan to the east, Michigan to the northeast, and Lake Superior to the north.

The bulk of Wisconsin's population live in areas situated along the shores of Lake Michigan. The largest city, Milwaukee, anchors its largest metropolitan area, followed by Green Bay and Kenosha, the third- and fourth-most-populated Wisconsin cities respectively. The state capital, Madison, is currently the second-most-populated and fastest-growing city in the state. Wisconsin is divided into 72 counties and as of the 2020 census had a population of nearly 5.9 million.

Wisconsin's geography is diverse, having been greatly impacted by glaciers during the Ice Age with the exception of the Driftless Area. The Northern Highland and Western Upland along with a part of the Central Plain occupy the western part of the state, with lowlands stretching to the shore of Lake Michigan. Wisconsin is third to Ontario and Michigan in the length of its Great Lakes coastline. The northern portion of the state is home to the Chequamegon-Nicolet National Forest. At the time of European contact the area was inhabited by Algonquian and Siouan nations, and today is home to eleven federally recognized tribes. During the 19th and early 20th centuries, many European settlers entered the state, most of whom emigrated from Germany and Scandinavia. Wisconsin remains a center of German American and Scandinavian American culture, particularly in respect to its cuisine, with foods such as bratwurst and kringle. Wisconsin is home to one UNESCO World Heritage Site, comprising two of the most significant buildings designed by Wisconsin-born architect Frank Lloyd Wright: his studio at Taliesin near Spring Green and his Jacobs I House in Madison.

The Republican Party was founded in Wisconsin in 1854. In more recent years, Wisconsin has been a battleground state in presidential elections, notably in 2016 and 2020.

The state is one of the nation's leading dairy producers and is known as "America's Dairyland"; it is particularly famous for its cheese. The state is also famous for its beer, particularly and historically in Milwaukee, most notably as the headquarters of the Miller Brewing Company. Wisconsin has some of the most permissive alcohol laws in the country and is well known for its drinking culture. Its economy is dominated by manufacturing, healthcare, information technology, and agriculture—specifically dairy, cranberries and ginseng. Tourism is also a major contributor to the state's economy. The gross domestic product in 2020 was $348 billion.