1. On April 22, 1861, during the early days of the Civil War, the state of Maryland officially declared its allegiance to the Union. This decision was significant, as Maryland was a border state and its strategic location made it a key battleground throughout the conflict.

2. April 22, 1970 was the first ever Earth Day, a holiday that was founded in response to growing concerns about the environment and pollution. The event was celebrated across the United States, including in Maryland, where rallies and marches were held to advocate for environmental conservation and awareness.

3. In 1983, the Chesapeake Bay Bridge-Tunnel, which spans the mouth of the Chesapeake Bay, was officially opened to traffic. The bridge-tunnel is one of the longest in the world, spanning 17.6 miles, and provides an important transportation link between Maryland's Eastern Shore and the rest of the state.

4. On April 22, 1998, the University of Maryland Baltimore County (UMBC) men's lacrosse team set a record for most goals scored in a single game, with a staggering 40-3 victory over the University of Washington. The game remains one of the most lopsided victories in NCAA lacrosse history.

5. More recently, on April 22, 2021, Maryland Governor Larry Hogan signed a landmark police reform bill into law. The legislation, which was passed in response to the killing of George Floyd and other high-profile incidents of police violence, includes provisions for increased officer training, independent investigations of police misconduct, and greater transparency and accountability in law enforcement.