High five times on a nationwide level
September 10–24, 2002, the first anniversary of the September 11, 2001 attacks.
February 7–27, 2003, near the end of the Muslim religious holiday Hajj.
March 17 – April 16, 2003, around the beginning of U.S. and Coalition military action in Iraq.
May 20–30, 2003, after the Riyadh compound bombings and the Casablanca bombings.
December 21, 2003 – January 9, 2004, citing intelligence information suggesting large-scale attacks around the holiday season.
In addition, the alert has been raised to High on a select or partial basis three times:
August 1 – November 10, 2004,(ooooohhh election time) for specific financial institutions in northern New Jersey, New York, and Washington, D.C., citing intelligence pointing to the possibility of a car or truck bomb attack, naming specific buildings as possible targets.
July 7, 2005 – August 12, 2005, for mass transit systems only. after the 7 July 2005 London bombings despite the absence of "specific, credible information suggesting imminent attack"
August 10, 2006 – present, for all domestic airline flights and all international flights to or from the United States
for a total of 8 times over these 5 years...color sys. was replaced in 2011