Memorial Day is a United States federal holiday observed on the last Monday of May. Formerly known as Decoration Day, it commemorates U.S. men and women who died while in the military service. First enacted to honor Union soldiers of the American Civil War, it was expanded after World War I.
Many people observe this holiday by visiting cemeteries and memorials. A national moment of remembrance takes place at 3pm. Another tradition is to fly the flag of the United States at half mast from dawn until noon. Volunteers often place American flags on each grave site at National Cemeteries.
Memorial Day is a time for picnics, barbecues, family gatherings, and sporting events. One of the longest-standing traditions is the running of the Indianapolis 500, which has been held in conjunction with Memorial Day since 1911.