Washington ( CNN ) -- Soldiers placed small American flags at the graves of more than 260,000 service members in Arlington National Cemetery on Thursday ahead of the Memorial Day weekend . The United States Army 's 3rd U.S. Infantry Regiment has maintained the tradition , known as `` Flags-In , '' at the cemetery since 1948 . The regiment , also known as the `` Old Guard , '' sent every available soldier to cover the 624 acre military cemetery , according to the Army . Arlington National Cemetery is located in Northern Virginia across the Potomac River from the nation 's capital . Flags were also placed at the Tomb of the Unknowns by the Tomb Sentinels , and at the cemetery 's Columbarium . The flags will be removed after Memorial Day .
The flag-placing tradition dates from 1948 . Every available soldier from the U.S. Army 's 3rd Infantry Regiment takes part . Hide Caption