Why Fly American Flags at Half Mast?
In many countries this is seen as a symbol of respect, mourning, distress, or, in some cases, a salute. Strictly speaking, flags are said to be half-mast if flown from ships and half-staff if on land, although not all regional variations of English use "half-staff." According to the VA, flags are flown at half-staff when the “whole nation is at mourning.” Sometimes, individual states and cities will decide to honor a local or regional loss with a half-staff flag.
The flag should be flown half-staff on Memorial Day in remembrance of deceased service members, but only from dawn until noon. Then, the flag is quickly raised full staff until sunset to honor living military veterans. The American flag should be flown half-staff on these days, as well:
Peace Officers Memorial Day (May 15), unless that day is also Armed Forces Day (third Saturday in May).
Patriot Day (September 11)
National Fallen Firefighters Memorial Service (traditionally the first Sunday in October).
Pearl Harbor Remembrance Day (December 7)
While many might be tempted to simply raise a flag halfway up the pole and stop, or just lower it at the end of the day, there’s more ceremony involved than that. According to the flag code, “The flag, when flown at half-staff, should be first hoisted to the peak for an instant and then lowered to the half-staff position. The flag should be again raised to the peak before it is lowered for the day.”