Memorial Day is a U.S. federal holiday observed on the last Monday of May to honor American military personnel who have died in service to their country. It originated after the Civil War as “Decoration Day,” a time when communities decorated the graves of fallen soldiers. The first widely recognized observance was organized by the Grand Army of the Republic (GAR), a Union veterans’ group, which designated May 30, 1868, for decorating the graves of Union soldiers[1][5]. The holiday’s origins are complex, with multiple communities, especially in the North and South, claiming to be the birthplace of Memorial Day, including Waterloo, New York, which Congress officially recognized in 1966. Early commemorations involved both Union and Confederate graves, reflecting post-war reconciliation efforts[2][4]. The name “Memorial Day” became more common after World War II, officially replacing “Decoration Day” by federal law in 1967[4]. Congress passed the Uniform Monday Holiday Act in 1968, moving Memorial Day to the last Monday in May starting in 1971 to create a long weekend for federal employees, and formally establishing it as a federal holiday[3][4]. Over time, Memorial Day’s scope expanded from honoring only Civil War dead to commemorating all U.S. military personnel who died in all wars, including World War I, World War II, Korea, Vietnam, and more recent conflicts[3][5]. Today, Memorial Day remains a solemn day of remembrance, marked by ceremonies such as wreath-laying at national cemeteries and a National Moment of Remembrance at 3 p.m. local time. While it is often associated with family gatherings and barbecues, its core purpose is to honor the sacrifices of fallen service members[2][6]. Recent observances continue to emphasize remembrance alongside public and presidential ceremonies documented in national archives[5].