1. On April 22, 1837, the University of Michigan held its first commencement ceremony. Sixteen students received their degrees in a small ceremony held in a local church.

2. On April 22, 1884, the Detroit Tigers played their first-ever game as a professional baseball team. They were defeated by the Milwaukee Brewers, 1-0, in front of a crowd of 1,100 spectators.

3. The first Earth Day was celebrated on April 22, 1970, and it had a significant impact on Michigan history. In response to the event, Governor William G. Milliken signed the Michigan Environmental Protection Act into law the following year. This was the first comprehensive state law in the United States to address environmental protection.

4. April 22, 1990, marked the 20th anniversary of Earth Day and saw the signing of the first-ever international treaty on climate change: the United Nations Framework Convention on Climate Change. Michigan was a key player in the negotiations that led to the treaty, thanks in part to the work of Michigan Senator Carl Levin.

5. On April 22, 2015, the Michigan House of Representatives passed a bill allowing people to carry concealed weapons in many areas of public schools. The bill sparked controversy and debate across the state, with proponents arguing that it would increase safety and opponents expressing concern about the potential for accidents and violence.