The U.S. celebrates Memorial Day. Officially, Memorial Day, observed on the last Monday in May, has been set aside to honor all who died during military service throughout U.S. history. Congress declared Memorial Day a national federal holiday in 1971.
In Pictures: US Observes Memorial Day

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President Donald Trump attends a wreath laying ceremony at Arlington National Cemetery, May 29, 2017, in Arlington, Virginia.

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Members of the audience stand as flag bearers walk into the Memorial Amphitheater in Arlington National Cemetery in Arlington, May 29, 2017, to begin the Memorial Day ceremony.

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President Donald Trump speaks at the Memorial Amphitheater in Arlington National Cemetery in Arlington, Virginia, May 29, 2017, during a Memorial Day ceremony.

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World War II veteran and Pearl Harbor survivor Armando "Chick" Galella (L) tosses a floral wreath following an annual Memorial Day commemoration ceremony at the Intrepid museum in New York, May 29, 2017.