Monday, May 28, 2012
Memorial Day was originally known as "Decoration Day," a reference to the practice of decorating the graves of war veterans. In 1971, Congress declared Memorial Day a federal holiday to be celebrated on the last Monday in May. On May 2, 2000, then-President Bill Clinton issued a memorandum calling on Americans "to pause for one minute at 3:00 p.m. (local time) on Memorial Day, to remember and reflect on the sacrifices made by so many to provide freedom for all."
You can find more information about the history of Memorial Day from the History Channel.