National POW/MIA Recognition Day: September
Before 1979, there were no official commemorations held to honor America's POW/MIAs. That year resolutions were passed in the Congress and a national ceremony was held at the National Cathedral, Washington, D.C.
Every year the US Congress continued passing legislation observing a National POW/MIA Recognition Day. In 1995 that changed and now the US President signs a yearly proclamation observing the day.
During the 1980's, the American Ex-POWs decided on establishing April 9th as the date of observance. That day was chosen because it was the date, during World War II, that the largest number of Americans were captured.
Eventually in an effort to accommodate all returned POWs and all Americans still missing and unaccounted for, from all wars, the third Friday in September was proposed - a date not associated with any particular war. This is the date on which the holiday is now observered
Ceremonies observing National POW/MIA Recognition Day are held throughout the nation and around the world on military installations, ships at sea, state capitols, at schools, churches, national veteran and civic organizations, police and fire departments, fire stations, etc. The POW/MIA flag is flown and the focus of the day is to ensure that America remembers its responsibility to stand behind those who serve their nation and do everything possible to account for those who do not return.
Observed: Third Friday in September