“How long should an US flag be flown at half mast?
The U.S. President can dictate by proclamation when, and for how long, the American flag is flown at half-mast. According to the Department of Veterans Affairs, the flag should fly at half-staff for 30 days following the death of a current or former president, and for 10 days after the death of the vice president and other government officials.”
Additionally, he/she can determine other occasions for it to be flown at half-staff and for how long: President Biden issued the proclamation on Friday, April 16, after eight people were killed when a gunman opened fire inside the Indianapolis FedEx building. Following the mass shooting, President Biden said flags would fly at half-staff through to sunset on Tuesday, April 20.