1. Michigan became a state on September 15, 1837. This day is celebrated as Michigan's Statehood Day, and it marks the day when Michigan officially joined the United States as the 26th state.

2. On September 15, 1923, the Michigan State Fair opened for the first time at its new location in Detroit. It had previously been held in several other locations in the state.

3. The Mackinac Bridge, which spans the Straits of Mackinac and connects Michigan's upper and lower peninsulas, was opened to traffic on September 15, 1957. It is one of the longest suspension bridges in the world.

4. The first Michigan Renaissance Festival opened on September 15, 1979, in Holly, Michigan. The festival, which is still held annually, features medieval-themed events, entertainment, and food.

5. On September 15, 2017, Michigan became the first state to be granted a permit to operate a driverless vehicle on public roads without a human driver. The permit was granted to the American automaker, General Motors.