The timing of President Jimmy Carter’s death on Sunday means U.S. flags will be at half-staff on Trump’s inauguration day next month. Flags are to be flown at half-staff for 30 days from the day of a current or former president’s death “on all buildings, grounds, and naval vessels of the Federal Government in the District of Columbia and throughout the United States and its Territories and possessions,” as codified in the Office of the Federal Register in 1954.