1. The Battle of Front Royal occurred on April 30, 1862, during the American Civil War. Confederate forces under General Stonewall Jackson defeated Union forces, capturing over 900 prisoners and securing much-needed supplies for their army.

2. On April 30, 1947, the Maryland State Park System was established, with the purpose of preserving natural and historical resources and providing recreational opportunities for the public.

3. The Maryland State Archives, which houses important historical documents and records, was established on April 30, 1935.

4. In 1970, the first Earth Day was celebrated on April 30 in Maryland and across the United States, raising awareness and promoting environmental activism.

5. On April 30, 1789, George Washington was inaugurated as the first President of the United States in New York City. While this event did not occur in Maryland specifically, it is an important part of American history that has impacted the entire country, including Maryland.