To position the flag at half-staff, first raise the flag to the peak of the staff for an instant and then lower it to the half-staff position -- roughly halfway between the top and bottom of the staff. Before lowering it for the day, raise the flag again to the peak of the pole for a moment.
By order of the President, the flag shall be flown at half-staff upon the death of principal figures of the United States Government and the Governor of a State, territory, or possession, as a mark of respect to their memory. In the event of the death of other officials or foreign dignitaries, the flag is to be displayed at half-staff according to U.S. Presidential instructions, or in accordance with recognized customs.
In the event of the death of a present or former official of the government of any State, territory, or possession of the U.S., the Governor of that State, territory, or possession may proclaim that the National Flag shall be flown at half-staff.
The flag shall be flown at half-staff for:
thirty days following the death of the President or a former President
ten days following the day of death of the Vice President, the Chief Justice or a retired Chief Justice of the United States, or the Speaker of the House of Representatives
from the day of death until interment of an Associate Justice of the Supreme Court, a Secretary of an executive or military department, a former Vice President or the Governor of a State, territory, or possession
on the day of death and the following day for a Member of Congress
Peace Officers Memorial Day, unless that day is also Armed Forces Day.
In a case where the flag is fixed to the pole (often in residential situations) it cannot be flown at half staff. In this instance, it is proper to attach two black ribbons to the end of the pole to show respect.
The flag should be displayed from sunrise to sunset on all days, but especially on the following national and state holidays:
New Year's Day, January 1
Martin Luther King, Jr. Day, third Monday in January
Inauguration Day, January 20
Lincoln's Birthday, February 12
Washington's Birthday, third Monday in February
Easter Sunday (variable)
Mother's Day, second Sunday in May
Peace Officers Memorial Day, May 15
Armed Forces Day, third Saturday in May
Memorial Day, the last Monday in May (half-staff until noon)
Flag Day, June 14
Father's Day, third Sunday in June
Independence Day, July 4
Korean War Veterans Day, July 27
Labor Day, first Monday in September
Patriot Day, September 11 (half staff)
Constitution Day, September 17
Gold Star Mother's Day, last Sunday in September
Fire Fighters Memorial Day, the Sunday before or on October 9th
Columbus Day, second Monday in October
Navy Day, October 27
Veterans Day, November 11
Thanksgiving Day, fourth Thursday in November
Pearl Harbor Rememberance Day, December 7 (half staff All Day)
Christmas Day, December 25
State Birthdays and Holidays
All Election Days
(and other days that may be proclaimed by the President of the US or the Governor of a state)