1. On March 21, 1638, the first Maryland court session was held in St. Mary's City. This marked the beginning of a long tradition of Maryland's legal system.

2. In 1825, the Chesapeake and Ohio Canal Company was chartered on March 21. This construction of the canal was a major engineering feat, spanning 184.5 miles from Georgetown in Washington, DC to Cumberland, Maryland.

3. On March 21, 1860, Maryland's first telegraph line was completed between Baltimore and Frederick. This marked a major advancement in communication and paved the way for future technological breakthroughs.

4. March 21, 1902, marked the dedication of the Washington Monument in Baltimore, Maryland. Standing over 170 feet tall, the monument was built as a tribute to the first President of the United States, George Washington.

5. On March 21, 1965, a student-led civil rights march took place in Montgomery County, Maryland. The march was in response to segregation in local schools and was a key event in the civil rights movement in Maryland.