Flags are flown at half-mast as a sign of mourning, respect, or distress. This tradition dates back to the 17th century and is used to honor the deceased, especially prominent government officials, military members, or victims of national tragedies. The lowered flag leaves space for an "invisible flag" symbolizing the loss or death, serving as a collective expression of grief and remembrance.

Currently, flags are at half-mast in honor of Charlie Kirk, as ordered by the President of the United States from September 10 to 14, 2025. This act marks respect for his memory and is part of official national mourning protocols.