1. Emancipation Day: April 15 is celebrated as Emancipation Day in the District of Columbia, commemorating the day in 1862 when President Abraham Lincoln signed the Compensated Emancipation Act freeing nearly 3,100 enslaved people in the district.

2. Tax Day: While April 15 is also widely known as Tax Day in the United States, the deadline for filing federal income tax returns has been changed to May 17, 2021, due to the ongoing COVID-19 pandemic.

3. Cherry Blossom Peak: The National Park Service predicts the peak bloom of the cherry blossom trees in Washington D.C. usually falls around April 1-10, but in some years it can be as late as April 15.

4. Assassination attempt on President Franklin D. Roosevelt: On April 15, 1933, a lone gunman fired shots at President Franklin D. Roosevelt in Miami, Florida, but missed and subsequently wounded the mayor of the city.

5. Founding of Georgetown University: On April 15, 1789, Georgetown University was founded in Washington D.C. by the Society of Jesus, making it the oldest Catholic and Jesuit-affiliated institution of higher education in the United States.