The U.S. Flag Code, adopted in 1923 and amended by Public Law 94-344 in 1976, states "It is the universal custom to display the flag only from sunrise to sunset ... However, when a patriotic effect is desired, the flag may be displayed 24 hours a day if properly illuminated during the hours of darkness."
When flags or pennants of states, cities, or societies are flown with the national flag on the same halyard, the U.S. flag should fly at the peak, above all others.
If other flags are flown from adjacent staffs, the U.S. flag should always be to the right of all others and should be hoisted first and lowered last.
Flags of other nations must be flown from separate flagpoles of equal height, and all flags should be approximately equal in size with the U.S. flag. International usage forbids the display of the flag of one nation above that of another nation in time of peace.