The POW/MIA flag was created by the National League of Families and officially recognized by the Congress in conjunction with the Vietnam War POW/MIA issue, "as the symbol of our Nation's concern and commitment to resolving as fully as possible the fates of Americans still prisoner, missing and unaccounted for in Southeast Asia, thus ending the uncertainty for their families and the Nation."
The original design for the flag was created by Newt Heisley in 1972 The National League of Families then-national coordinator, POW wife Evelyn Grubb, oversaw its development and also campaigned to gain its widespread acceptance and use by the United States government and also local governments and civilian organizations across the United States.
In 1971, while the Vietnam War was still being fought, Mary Helen Hoff, the wife of a service member missing in action and member of the National League of Families of American Prisoners and Missing in Southeast Asia, recognized the need for a symbol of U.S. POW/MIAs, some of whom had been held captivity for as many as seven years. The flag is black, and bears in the center, in black and white, the emblem of the league. The emblem was designed by Newt Heisley, and features a white disk bearing in black silhouette the bust of a man (Jeffery Heisley), watch tower with a guard on patrol, and a strand of barbed wire; above the disk are the white letters POW and MIA framing a white 5-pointed star; below the disk is a black and white wreath above the white motto: "You are not Forgotten." The POW/MIA was flown over the White House for the first time in September 1982 The flag has been altered many times; the colors have been switched from black with white – to red, white and blue – to white with black; the POW/MIA has at times been revised to MIA/POW.
On March 9, 1989, a league flag that had flown over the White House on the 1988 National POW/MIA Recognition Day was installed in the U.S. Capitol rotunda as a result of legislation passed by the 100th Congress. The league's POW-MIA flag is the only flag ever displayed in the rotunda, and the only one other than the Flag of the United States to have flown over the White House. The leadership of both houses of Congress hosted the installation ceremony in a demonstration of bipartisan congressional support.
On August 10, 1990, the 101st Congress passed U.S. Public Law 101-355, recognizing the National League of Families POW/MIA Flag and designating it "as a symbol of our Nation's concern and commitment to resolving as fully as possible the fates of Americans still prisoner, missing and unaccounted for in Southeast Asia, thus ending the uncertainty for their families and the Nation." Beyond Southeast Asia, it has been a symbol for POW/MIAs from all U.S. wars.
With the passage of Section 1082 of the 1998 Defense Authorization Act during the first term of the 105th Congress, the POW/MIA Flag was specified to fly each year on:
- Armed Forces Day—Third Saturday in May
- Memorial Day—Last Monday in May
- Flag Day—June 14
- Independence Day—July 4
- National POW/MIA Recognition Day—Third Friday in September
- Veterans Day—November 11
The POW/MIA flag will be flown on the grounds or the public lobbies of major military installations as designated by the U.S. Secretary of Defense, all Federal National Cemeteries, the Korean War Veterans Memorial, the Vietnam Veterans Memorial, the White House, the United States Post Offices and at official offices of the Secretaries of State, Defense and Veterans Affairs, and Director of the Selective Service System. Civilians are free to fly the POW/MIA flag whenever they wish.
In the U.S. armed forces, the dining halls, mess halls and chow halls display a single table and chair in a corner draped with the POW-MIA flag as a symbol for the missing, thus reserving a chair in hopes of their return.
Other color patterns exist: the orange and black pattern was run by Outpost Flags at the time of Harley Davidson's 100th anniversary, so that the bikers would help keep the issue alive and in the forefront of American politics. There are red and white versions, which some say are to cover more recent military actions, but this is not official policy. There are black and red versions available as well.
POW/MIA Highway is the official name of Long Island's Sunrise Highway.
When displayed from a single flagpole, the POW/MIA flag should fly directly below, and be no larger than, the United States flag. If on separate poles, the U.S. flag should always be placed to the right of other flags (the viewer's left; the flag's own right). On the six national observances for which Congress has ordered display of the POW/MIA flag, it is generally flown immediately below or adjacent to the United States flag as second in order of precedence.
- POW/MIA bracelet
- Vietnam War POW/MIA issue
- Sybil Stockdale
- Hỏa Lò Prison (Hanoi Hilton)
- Vietnam Veterans Memorial
- Japanese prisoners of war in the Soviet Union
- Jose, Carol and Grubb, Evelyn; You Are Not Forgotten: A Family's Quest for Truth and the Founding of the National League of Families; Vandamere Press (New York); 2008. ISBN 0-918339-71-5.
- "Evelyn Fowler Grubb, 74, Leader Of a Group Supporting P.O.W.'s". The New York Times. January 4, 2006.
- "Newt Heisley, 1920-2009: WW II veteran designed POW/MIA flag", Associated Press, Chicago Tribune, May 19, 2009.
-  "Symbol of a Nation's Concern: The POW/MIA Flag and Newton Heisley, The VVA Veteran, July/August 2009
-  "The Story of the POW/MIA Flag" in Vietnam magazine, June 2012
- History of the POW/MIA flag on the league's website
- Video of C-SPAN special segment Story of how the "POW/MIA You Are Not Forgotten" Flag was created
- The POW/MIA Flag U.S. Department of Veterans Affairs
- POW/MIA (U.S.) at Flags of the World