1. In 1898, the Wisconsin State Historical Society was founded on June 20th. The society aims to collect, preserve, and share historical information about the state.

2. On June 20, 1915, the University of Wisconsin basketball team defeated Harvard in the first-ever national championship game for basketball. The game was played in Madison, Wisconsin, and marked a milestone in the history of college basketball.

3. In 1940, the first McDonald's restaurant in Wisconsin opened on June 20th in Milwaukee. The fast-food chain has since become a fixture in the state and across the country.

4. June 20th, 1988, was designated as "Gay Freedom Day" in Milwaukee by the city's common council. The designation was in recognition of the lesbian, gay, bisexual, and transgender community's contributions to the city and the fight for equal rights.

5. In 2002, the Wisconsin Supreme Court ruled on June 20th that the state's school voucher program was unconstitutional. The decision was highly controversial and sparked a heated debate about the role of government in education.