National Flag at Half Staff
When a president, former president or president-elect dies, the flag will be flown at half staff for 30 days from the date of death during the period of reveille to retreat.
When a vice president, chief justice or retired chief justice of the United States or speaker of the House of Representatives dies, the flag will be flown at half staff for 10 days from the day of death during the period of reveille to retreat.
There are specific guidelines for flying the flag for other individuals, ranging from an associate justice of the Supreme Court to retired enlisted service members. The flag might fly at half staff at all installations or only at the military installation while the funeral is being conducted.
The extent of the flag flying at half staff depends on the rank and or position of the deceased person.
When the president directs that the flag be flown at half staff at military facilities, on naval vessels and at stations abroad, it will be so flown whether or not the flag of another nation is flown at full staff alongside the U.S. flag.
Information gathered from the Army Regulation 600-25.