Dad is buried at Arlington Cemetery. Each year for the last 40 years soldiers from the 3rd U.S. Infantry place a single American flag at each grave at the beginning of the Memorial Day weekend. It's called the Flags-in ceremony. It takes them around 3 hours to place 260,000 flags on the graves. Then the soldiers stay in the cemetery for the entire weekend to make sure all the graves keep their flags.
I always think of the soldier who places the flag at my Dad's grave and hope that he or she is never in harm's way.