1. It is the universal custom to display the flag only from sunrise to sunset on buildings and on stationary flagstaffs in the open. However, when a patriotic effect is desired, the flag may be displayed 24 hours a day if properly illuminated during the hours of darkness.
2. The flag should be hoisted briskly and lowered ceremoniously.
3. The flag should not be displayed on days when the weather is inclement, except when an all-weather flag is displayed.
4. The flag should be displayed on the following days: When to Fly the Flag
5. The flag should be displayed daily on or near the main administration building of every public institution.
6. The flag should be displayed in or near every polling place on election days.
7. The flag should be displayed during school days in or near every schoolhouse.
Portions reprinted from the CRS Report for Congress, The United States Flag: Federal Law Relating to Display and Associated Questions, Updated July 5, 2007
Flag Etiquette - Time and Occasions for Display of the U.S. Flag