The U.S. flag has been modified 26 times since its adoption in 1777. Today's 50-star flag, created in 1960, has been in use the longest. Check out: Flag Day 2013: 9 things you never knew about the American Flag for interesting reading/facks sbout this day and the American Flag.
Additional recommended reading is How to display the American flag, By Alexia Elejalde-Ruiz, Chicago Tribune
Are you up to date on flag custom; which days are appropriate to fly your flag? The answer is every day, but there are special days when the flag should be displayed.
Please review my 2011 article regarding Flag Day: Today, June 14, is Flag Day, a special day to fly the US Flag. This article contains links to more information regarding flag customs including:
Air Force Association
UNITED STATES CODE
(Display of U.S. flag)
Title 36, Chapter 10 PATRIOTIC CUSTOMS
Sec. 174. Time and occasions for display
And a list of the dates that we should display the U.S. Flag.