According to the National Flag Foundation and the Flag Research Center, when the US flag is displayed on a shor staff or on a floor mounted staff where it cannot be lowered to half staff, a proper way to indicate mourning is by tying a black bow made of ribbon above a full-staffed US flag.

By order of Congress, the five days that the US flag should be displayed at half-staff are:

• May 15, Peace Officer's Memorial Day
• Memorial Day, the last Monday in May. Only till noon, then the flag is raised to full staff.
• July 27th, Korean War Vereran's Armistice Day
• September 11th, Patriot's Day
• December 7th, Pearl Harbor Remembrance Day