1. In 1970, the first Earth Day was observed in Massachusetts and throughout the United States. It was organized by local activist Denis Hayes and brought together millions of people to raise awareness about environmental issues.

2. On April 22, 1621, the first treaty between the Pilgrims and Native Americans was signed in Massachusetts. The treaty was signed between Massasoit, the sachem or leader of the Wampanoag tribe, and Governor John Carver of the Plymouth Colony. The treaty established a peaceful relationship between the two groups that lasted for several decades.

3. On April 22, 1861, the first Massachusetts volunteer regiment was mustered in for service in the Civil War. Known as the "Massachusetts 6th," it was one of the first regiments to answer President Lincoln's call for volunteers after the attack on Fort Sumter.

4. In 1930, the Boston Marathon was held for the first time on April 19, which coincided with Patriots' Day, a Massachusetts state holiday. However, in 1969, the marathon was moved to the third Monday in April, which is now known as "Marathon Monday" and is a major event in the state.

5. On April 22, 1993, a massive fire broke out in Waco, Texas, at the compound of the Branch Davidian cult. Four Massachusetts residents were among the 80 people who died in the siege and resulting fire. The event sparked controversy and debate over government intervention in religious groups.