Janesville, WI

The Rock River divides Janesville along a boundary recognized in the 1825 Treaty of Prairie du Chien: land west of the river was Ho-Chunk territory, while land east was Potawatomi territory. The Rock County seat had 65,615 residents in 2020 and an estimated 66,428 in 2024. Flour and lumber mills developed along the river. During the Civil War, area farms sold grain to the Union Army, and Rock County supplied one of Wisconsin’s highest numbers of enlistees. Afterward, agricultural growth supported foundries and farm-equipment makers including the Janesville Machine Company and Rock River Iron Works. General Motors operated the Janesville Assembly Plant from 1919 to 2008. The 1857 Italian Villa–style Lincoln-Tallman House is among the city’s registered historic sites. Janesville’s 64 improved parks, boat launches, golf courses, and nature trails underpin its “Wisconsin’s Park Place” nickname, and most city hiking and bicycling trails connect with the Ice Age Trail.