Americans celebrated Memorial Day this year on Monday May 30. But do you know why we observe Memorial Day? After the Civil War, a group of veterans created a day to remember those who had served. They called it Decoration Day. They thought it would be a day for Americans to decorate the graves of loved ones who had died. The first large observance of this day was held in 1868. Later Memorial Day was changed to honor people who died in all American wars. Congress declared Memorial Day a national holiday in 1971. Today it is on the last Monday each May.