-- More than 1,000 soldiers walked the rows of Arlington National Cemetery Thursday with a special task: honor each grave marker with an American flag.
The tradition, called Flags In, has taken place before Memorial Day weekend for more than 60 years.
The soldiers of the 3rd U.S. Infantry Regiment, also known as the Old Guard, placed a small flag in front of more than 230,000 headstones at Arlington National Cemetery.
The solemn event takes four hours, and the soldiers leave no grave unmarked, using their feet to measure how far the flag will be placed from the grave marker.
In addition to Arlington National Cemetery, the memorials, Tomb of the Unknown Soldier, and the Solders' and Airmen's Home National Cemetery are adorned with flags.
In 1948, the Old Guard was designated as the Army's official ceremonial unit.
The regiment also serves as an escort to the president and provides security to Washington, DC, in times of national emergency.