1. On March 4, 1681, the Maryland Assembly passed a law that prohibited the sale of slaves imported into the colony for a period of time. This was a significant step towards ending the practice of slavery in Maryland.

2. In 1776, the Maryland Convention meeting in Annapolis declared its support for the Continental Congress and the fight for independence from Great Britain. This helped to galvanize the revolutionary spirit in Maryland and the rest of the colonies.

3. On March 4, 1861, Abraham Lincoln was inaugurated as President of the United States for his first term. His election had significant implications for Maryland, which was a slave state at the time, and would soon become embroiled in the Civil War.

4. A major snowstorm hit Maryland on March 4, 1932, causing widespread disruption to travel and commerce. The storm was so severe that it was dubbed the "Knickerbocker Storm" after the collapse of the roof of the Knickerbocker Theatre in Washington D.C. killed 98 people.

5. The Chesapeake Bay Bridge–Tunnel, a 23-mile long bridge and tunnel complex linking the Eastern Shore of Maryland with Virginia, was officially opened on March 4, 1964. The construction of the bridge–tunnel was a significant engineering feat, and allowed for increased trade and travel between the two states.