Memorial Day is a federal holiday in the United States for remembering the people who died while serving in the country's armed forces.The holiday, which is observed every year on the last Monday of May, originated as Decoration Day after the American Civil War in 1868, when the Grand Army of the Republic, an organization of Union veterans — established it as a time for the nation to decorate the graves of the war dead with flowers. By the 20th century, competing Union and Confederate holiday traditions, celebrated on different days, had merged, and Memorial Day eventually extended to honor all Americans who died while in the military service. It typically marks the start of the summer vacation season, while Labor Day marks its end.
Many people visit cemeteries and memorials, particularly to honor those who have died in military service. Many volunteers place an American flag on each grave in national cemeteries.