On Memorial Day, each gravesite of the more than 260,000 U.S. service members buried at Arlington National Cemetery will have a small American flag carefully positioned exactly one boot’s length away from the headstone. The flags were placed by 1,500 soldiers from the Army’s 3rd Infantry Regiment, better known as The Old Guard. The regiment has carried out the tradition, known as “Flags In,” just before Memorial Day every year since 1948.