1. On May 10, 1775, the Second Continental Congress authorized the raising of troops in Massachusetts, marking the beginning of the American Revolution. The Massachusetts Provincial Congress had already begun enlisting men in response to the skirmishes at Lexington and Concord on April 19.

2. May 10, 1869, marked the completion of the first transcontinental railroad in the United States, connecting the Central Pacific Railroad in California with the Union Pacific Railroad in Nebraska. The project was a significant achievement in American transportation history.

3. On May 10, 1893, the World's Columbian Exposition opened in Chicago, Illinois. Massachusetts was among the 46 states and territories represented at the fair, which celebrated the 400th anniversary of Christopher Columbus's arrival in the Americas.

4. Massachusetts Governor William Weld signed a landmark welfare reform bill into law on May 10, 1995. The legislation included strict work requirements for recipients of public assistance and was seen as a model for other states to follow.

5. May 10, 2004, marked the first legal same-sex marriages in the United States, which took place in Massachusetts following a landmark court ruling. The state became the first in the nation to recognize same-sex marriage, paving the way for others to follow.