1. St. Patrick's Day: March 17th is St. Patrick's Day, a holiday widely celebrated by people of Irish descent in Washington and across the United States. The day is often marked by parades, parties, and other festivities, with Washington's St. Patrick's Day Parade being one of the largest and most popular events in the city.

2. Founding of Washington D.C.: March 17, 1790, is the date when President George Washington signed the Residence Act, which established Washington D.C. as the capital of the United States. This date is an important milestone in the city's history and is commemorated annually.

3. Cherry Blossom Festival: Washington's National Cherry Blossom Festival usually begins around March 17th and is one of the city's most popular attractions. It commemorates the gift of 3,000 cherry trees from the Mayor of Tokyo to the city of Washington D.C. in 1912.

4. National Mall: The National Mall, an iconic park in the center of Washington D.C., was officially opened to the public on March 17, 1840. The park is home to many of the city's most famous monuments and landmarks, including the Washington Monument and the Lincoln Memorial.

5. Women's suffrage: On March 17, 1917, women picketed outside the White House demanding the right to vote. This event was part of the larger women's suffrage movement, which eventually culminated in the passage of the 19th Amendment to the U.S. Constitution in 1920, giving women the right to vote.