Constitution Day is the Federal observance that recognizes the adoption of the United States Constitution and those who have become U.S. citizens. It is normally observed on September 17, the day in 1787 that delegates to the Constitutional Convention signed the document in Philadelphia.

Independence Day, known as the Fourth of July, is a federal holiday in commemorating the Declaration of Independence, which was ratified by the Second Continental Congress on July 4, 1776, establishing the United States of America.

Memorial Day is a federal holiday honoring and mourning the U.S. military personnel who died while serving in the United States Armed Forces. From 1868 to 1970, it was observed on May 30. Since 1971, it is observed on the last Monday of May.