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.
The flag should be displayed on all days, especially on New Year’s Day,
January 1; Inauguration Day, January 20; Martin Luther King Jr.’s birthday, the
third Monday in January;15 Lincoln’s Birthday, February 12; Washington’s
Birthday, third Monday in February; Easter Sunday (variable); Mother’s Day,
second Sunday in May; Armed Forces Day, third Saturday in May; Memorial
Day (half-staff until noon), the last Monday in May; Flag Day, June 14;
Independence Day, July 4; Labor Day, first Monday in September; Constitution
Day, September 17; Columbus Day, second Monday in October; Navy Day,
October 27; Veterans Day, November 11; Thanksgiving Day, fourth Thursday
in November; Christmas Day, December 25; and such other days as may be
proclaimed by the President of the United States; the birthdays of States (date
of admission); and on State holidays.
The flag should not be displayed on days when the weather is inclement, except
when an all-weather flag is displayed
The flag of the United States of America should be at the center and at the
highest point of the group when a number of flags of States or localities or
pennants of societies are grouped and displayed from staffs.
When flags of States, cities, or localities, or pennants of societies are flown on
the same halyard with the flag of the United States, the latter should always be
at the peak. When the flags are flown from adjacent staffs, the flag of the
United States should be hoisted first and lowered last. No such flag or pennant
may be placed above the flag of the United States or to the United States flag’s
right.
When flags of two or more nations are displayed, they are to be flown from
separate staffs of the same height. The flags should be of approximately equal
size. International usage forbids the display of the flag of one nation above that
of another nation in time of peace.
The length of the flag should be at least 1/4 the height of the pole.
15 Ft Pole: 3'x5'
20 Ft Pole: 3'x5'
25 Ft Pole: 4'x6'
*Some content in this FAQ is gleaned from the CRS Report for Congress: The United States Flag: Federal Law Relating to Display and Associated Questions