UNITED STATES CODE
(Display of U.S. flag)
Title 36, Chapter 10 PATRIOTIC CUSTOMS
Sec. 174. Time and occasions for display
The flag should be displayed on all days, especially on New Year's Day, January 1; 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; Armed Forces Day, third Saturday 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.
Questions about how and when to properly display the US Flag? One of many online resources: http://www.afa.org/members/uscode.asp