1. On June 15, 1846, the Wisconsin Territory was established by an act of the U.S. Congress, encompassing much of the present-day states of Wisconsin, Minnesota, Iowa, and parts of North and South Dakota. Wisconsin became a state two years later, in 1848.

2. The first public library in Wisconsin was established in Milwaukee on June 15, 1878. The library was founded by the Young Men's Association and housed in a temporary location until a permanent building was constructed. Today, the Milwaukee Public Library system is one of the largest in the country, with 13 branches serving the city of Milwaukee.

3. On June 15, 1911, the Wisconsin State Capitol building in Madison was dedicated. The building, designed by architect George B. Post in the Beaux-Arts style, features a dome topped with a statue of "Wisconsin" by sculptor Daniel Chester French. The Capitol is home to the governor's office, the state legislature, and the Wisconsin Supreme Court.

4. Wisconsin native Laura Ingalls Wilder was born on June 15, 1867, in Pepin County. Wilder is best known for her series of "Little House" books, which recount her childhood experiences living on the frontier in the late 1800s. Many of the events in the books were based on her own life, including her family's years in Wisconsin.

5. On June 15, 1988, the first official Gay Pride Day was held in Milwaukee. The event, which attracted thousands of participants, was organized by the Milwaukee Lesbian/Gay Pride Committee to celebrate the contributions and diversity of the LGBTQ+ community in the city. Today, Milwaukee's Pridefest is one of the largest LGBTQ+ festivals in the Midwest, attracting over 40,000 people each year.