1. On June 21, 1964, a tornado struck the city of Appleton, Wisconsin, causing significant damage and killing one person. The tornado was estimated to have been an F3 on the Fujita scale, with wind speeds of up to 206 miles per hour.

2. June 21, 1970, marks the first Earth Day held in Wisconsin. The day was celebrated at Blue Mounds State Park, with activities such as nature hikes, music, and speeches on environmental conservation.

3. In 1980, on June 21, the Wisconsin State Historical Society celebrated its 125th anniversary. The society was founded in 1855 and is the oldest historical society in the United States.

4. The Milwaukee Bucks won their first NBA championship on June 21, 1971, defeating the Baltimore Bullets in four games. The team was led by future Hall of Famers Kareem Abdul-Jabbar and Oscar Robertson.

5. On June 21, 1898, the USS Wisconsin was launched at the Philadelphia Naval Shipyard. The battleship would go on to serve in both World Wars and the Korean War, earning five battle stars for its service. Today, the ship is preserved as a museum in Norfolk, Virginia.