1. The American Civil War brought significant changes to Maryland, and May 10, 1861 saw the first Union soldiers arrive in the state, occupying Baltimore's Federal Hill in an effort to keep the city under Union control. This event marked the beginning of a four-year struggle for Maryland's allegiances during the war.

2. On May 10, 1877, Baltimore was the site of a deadly railroad strike that lasted several days. The Great Railroad Strike of 1877 was a nationwide labor protest that began in West Virginia and spread quickly across the country.

3. May 10, 1893, marked the opening of the World's Columbian Exposition in Chicago, Illinois. Several exhibits showcasing Maryland's industry and agriculture were on display at the fair, including an exhibit on oyster farming on the Chesapeake Bay.

4. May 10, 1944, saw a devastating fire break out at the Baltimore port, destroying more than 30 buildings and causing millions of dollars in damage. The fire burned for over 30 hours and was one of the largest ever recorded in the city's history.

5. On May 10, 1970, a Black student strike began at the University of Maryland, College Park, following the Kent State shootings in Ohio. The strike lasted for two weeks and resulted in the formation of the Black Student Union on campus.