1. Maryland became the seventh state to ratify the United States Constitution on June 1, 1788. The state's vote was crucial in securing the Constitution's adoption as it was the ninth state to do so, which was the minimum number required for the Constitution to go into effect.

2. The Chesapeake Bay Bridge-Tunnel, which spans 17.6 miles across the Chesapeake Bay and connects Virginia's Eastern Shore to Virginia Beach, opened on June 1, 1964. The bridge-tunnel is one of the longest in the world and is a major transportation route on the East Coast.

3. On June 1, 1843, the first baseball game in Maryland was played in Baltimore. The game was between the Maryland Club and the Knickerbocker Club of New York and was played at the Union Cricket Club. Baseball quickly became popular in Maryland and has a rich history in the state.

4. The famous American author, H.L. Mencken, was born in Baltimore on June 1, 1880. Mencken was known for his sharp wit and criticism of American society and culture. He was a prolific writer and editor, and his work helped shape American literature in the early 20th century.

5. June 1, 1842, marked the first day of operation for the B&O Railroad's passenger service in Maryland. The railroad, which was established in 1827, was the first common carrier railroad in the United States and played a vital role in the development of transportation in the state and the country.