Memorial Day originated in 1882, when it focused on those who died in military service during the Civil War. The holiday only expanded to include all military deaths after World War I and was not widely celebrated until after World War II. It finally became an official federal holiday in 1967.
There is no clear answer and many stories as to where Memorial Day originated. Although President Lyndon B. Johnson declared that the birthplace of Memorial Day was Waterloo, N.Y., several other cities claim the honor, including Charleston, S.C., and Columbus, Miss. One story states that the tradition of grave decorating began when two girls in Boalsburg, Pa., laid flowers on the graves of the fallen. More people joined in the tradition over the years.
A precursor to Memorial Day, Decoration Day, was celebrated in Waterloo, N.Y., starting on May 5, 1868, though the date later moved to May 30. For a while only the north celebrated this holiday for fallen Union soldiers. Memorial Day replaced Decoration Day in 1882. However, it took the expansion of Memorial Day to include all who died in active military service for the southern states to start celebrating it as well. It was made a federal holiday in 1967. In 1971, the holiday officially moved to the last Monday in May.