"On Memorial Day, a uniformed U.S. soldier plants American flags at gravesites at Arlington National Cemetery, Arlington, Virginia on May 30, 1994." Mark Reinstein/Corbis/Getty Images
"A young woman lies down on the grave of U.S. Marine Corps Lance Corporal Noah Pier on Memorial Day at Arlington National Cemetery May 31, 2010 in Arlington, Virginia. Pier was killed February 12, 2010 in Marja, Afghanistan." Chip Somodevilla/Getty Images
"A Memorial Day parade in Gray, Maine features 17 empty chairs. Each is painted with a veteran's name and displays a helmet. The May 28, 1991 parade float represents Maine troops who are prisoners of war or missing in action." Gene Willman/Portland Portland Press Herald/Getty Images
