(CNN)Here's some background information about Armed Forces Day, a holiday observed in some areas of the United States to honor all branches of the armed forces.
May 21, 2016 - Armed Forces Day.
Each year there is a theme. The theme of the first Armed Services Day was "Teamed for Defense."
July 26, 1947 - President Harry S. Truman signs the National Security Act into law, unifying "four branches of the military under a single executive authority, the Secretary of Defense." The decision to unify the different services under one Department leads to the creation of the National Military Establishment in 1947.
- Daily observances and festivities take place nationwide starting a week before the holiday.
- B-36 bombers fly over the capitals of every state.
- 10,000 troops and veterans march in Washington, D.C.
- More than 36,000 participants in a parade in New York City.
- Parades, air shows, receptions and other celebrations also take place.