30 May 1868
Perhaps inspired by unofficial memorial celebrations across the country, John A. Logan—then the commander of the Grand Army of the Republic (a Civil War veterans organization)—proclaimed the creation of Memorial Day (then called Decoration Day) for the first time on 5 May 1868. It was first observed on 30 May of that year, and the first celebration included placing flowers on the graves at Arlington National Cemetery. By 1890, all the Northern states recognized the holiday, and in 1971 the day was officially set as the last Monday in May. The day originally was meant to honor and remember Civil War dead, but after World War I it transformed into a day of remembrance for all war dead.