Americans began informally decorating the graves of soldiers who had died during the civil war as tributes. Known as Decoration Day until 1970, this informal celebration was declared a national holiday, Memorial Day, in 1971. It is celebrated on the last Monday in May to honor those who died in military service. According to history,.com
"It is unclear where exactly this tradition originated; numerous different communities may have independently initiated the memorial gatherings. And some records show that one of the earliest Memorial Day commemorations was organized by a group of formerly enslaved people in Charleston, South Carolina less than a month after the Confederacysurrendered in 1865. Nevertheless, in 1966 the federal government declared Waterloo, New York, the official birthplace of Memorial Day."