Marines at the 2010 Memorial Day Parade.
Organizers for the parade are preparing for more than 250,000 spectators to line Constitution Avenue and the National Mall.
Nearly 200 elements will take part in the parade: marching bands, active and retired military units, parade floats and of course hundreds of veterans from World Ward II to the current conflicts in Iraq and Afghanistan.
Special guests at this year's parade include actors Joe Mantegna and Gary Sinise, as well as Wheel of Fortune Host Pat Sajak. Korean War Veteran and moon-walker Buzz Aldrin will be there, as will members of the Tuskegee Airmen, the legendary unit of African-American pilots from World Ward II.
Locally, D.C. Mayor Vincent Gray will serve as an honorary grand marshal of the parade and some of the Pearl Harbor survivors from the D.C.-area will also be on hand.
The parade officially begins at 2 p.m. at the corner of Constitution Avenue and 7th Street NW. It will proceed west down Constitution, past the White House, ending at 17th Street.
Other Memorial Day events include a wreath-laying at the World War II Memorial at 9 a.m., and a breakfast hosted by President and Mrs. Obama at the White House for Gold Star Families, which are families who have lost a loved one in combat. After, the president heads to Arlington Cemetery to lay a wreath at the tomb of the unknowns.
In the afternoon, an observance takes place at the Vietnam Veterans Memorial at 1 p.m., with bagpiper Chris Jackson playing "Amazing Grace," and Tenley Westbrook will perform the National Anthem.