On May 5, 1868, General John A. Logan, leader of an organization for Northern Civil War veterans, called for a nationwide day of remembrance later that month. “The 30th of May, 1868, is designated for the purpose of strewing with flowers, or otherwise decorating the graves of comrades who died in defense of their country during the late rebellion, and whose bodies now lie in almost every city, village and hamlet churchyard in the land,” he proclaimed.

Freshly-placed flags on the graves of Civil War veterans in Green Mount Cemetery in Montpelier, Vermont

On the first Decoration Day, General James Garfield made a speech at Arlington National Cemetery, and 5,000 participants decorated the graves of the 20,000 Union and Confederate soldiers buried there.

Many Northern states held similar commemorative events and reprised the tradition in subsequent years; by 1890 each one had made Decoration Day an official state holiday. Southern states, on the other hand, continued to honor their dead on separate days until after World War I.

Memorial Day, as Decoration Day gradually came to be known, originally honored only those lost while fighting in the Civil War. But during World War I the United States found itself embroiled in another major conflict, and the holiday evolved to commemorate American military personnel who died in all wars.

For decades, Memorial Day continued to be observed on May 30, the date Logan had selected for the first Decoration Day. But in 1968 Congress passed the Uniform Monday Holiday Act, which established Memorial Day as the last Monday in May in order to create a three-day weekend for federal employees; the change went into effect in 1971. The same law also declared Memorial Day a federal holiday.

Memorial Day 2017 occurs on May 29; Memorial Day 2018 falls on May 28.