1. In 1908, the first electric streetcar was introduced in Milwaukee, which operated on September 21. The streetcar was a popular mode of transportation in the city until its discontinuation in 1958.

2. On September 21, 1929, the first airplane to land at the new Superior Municipal Airport in Douglas County arrived. The airport was originally built as a stopping point for flights between Chicago and Duluth, and today serves as an important transportation hub for the area.

3. In 1944, the Wisconsin Dells were officially designated as a state park on September 21. The Dells are known for their unique rock formations and scenic beauty, and have become one of the state's most popular tourist destinations.

4. The Packers played their first-ever game on September 21, 1919, against the Menasha Norths. The game took place at Hagemeister Park in Green Bay, which was the Packers' home field at the time.

5. On September 21, 1972, the University of Wisconsin-Madison became the first public university in the United States to offer a degree in women's studies. The program was designed to address the lack of representation of women's issues in traditional academic disciplines.