Here's a Milwaukee historical marker in the downtown worth taking in. The text reads:
Joshua Glover was a runaway slave who sought freedom in Racine in 1852. In 1854, his Missouri owner used the Fugitive Slave Act to apprehend him. This 1850 law permitted slave catchers to cross state lines to captured escaped slaves. Glover was taken to Milwaukee and imprisoned.
Word spread about Glover’s incarceration and a great crowd gathered around the jail demanding his release. They beat down the jail door and released Joshua Glover. He was eventually escorted to Canada and safety.
The Glover incident helped galvanize abolitionist sentiment in Wisconsin. This case eventually led the state supreme court to defy the federal government by declaring the Fugitive Slave Act unconstitutional.