1. On March 21, 1806, the construction of the National Road began in Cumberland, Maryland, which would eventually become the first federally funded road project in the United States. The road would eventually stretch all the way to Vandalia, Illinois and helped to connect the eastern and western regions of the country.

2. On March 21, 1871, the District of Columbia officially became the seat of the United States government when Congress passed the Organic Act, which established a government for the District and designated it as the capital of the country.

3. On March 21, 1914, the first cherry blossom trees were planted along the Tidal Basin in Washington D.C. as a gift from the city of Tokyo. The annual Cherry Blossom Festival has been celebrated in D.C. every year since 1935 and attracts thousands of visitors from around the world.

4. On March 21, 1945, the United States Senate ratified the United Nations Charter, confirming the country's commitment to the establishment of an international organization to promote peace and security around the world.

5. On March 21, 1963, the U.S. Supreme Court issued its decision in Gideon v. Wainwright, which guaranteed the right to legal representation for all criminal defendants regardless of their ability to pay. The landmark ruling has been credited with revolutionizing the criminal justice system in the U.S. and ensuring that everyone is afforded a fair trial.