1. Maryland became the seventh state to ratify the United States Constitution on May 1, 1788. The state's ratification helped to secure the necessary nine states needed for the constitution to go into effect.

2. On May 1, 1865, President Andrew Johnson ordered the release of all Confederate prisoners of war held in Maryland. The order came just weeks after General Robert E. Lee's surrender at Appomattox Court House, Virginia, effectively ending the Civil War.

3. In the early 1900s, May Day (May 1) was celebrated as a workers' holiday in Maryland and throughout the United States. Labor unions would hold parades and rallies to advocate for better working conditions and wages.

4. On May 1, 1969, a group of University of Maryland students led a protest against the Vietnam War, calling for an end to the conflict and for the university to halt its involvement with military research. The demonstration ended with police using tear gas to disperse the crowd.

5. May 1, 2013 marked the passage of Maryland's Marriage Equality Act, which legalized same-sex marriage in the state. Maryland was the eighth state in the United States to pass such a law.