The United States uses nine time zones. From east to west they are Atlantic Time Zone, Eastern Time Zone, Central Time Zone, Mountain Time Zone, Pacific Time Zone, Alaska Time Zone, Hawaii-Aleutian Time Zone, Samoa Time Zone and Chamorro Time Zone. View the standard time zone boundaries.
Daylight Saving Time begins at 2:00 a.m. local time on the second Sunday in March. On the first Sunday in November areas on Daylight Saving Time return to Standard Time at 2:00 a.m. The names and abbreviations frequently used to indicate the current local time in each time zone change along with Daylight Saving Time. Eastern Standard Time (EST) becomes Eastern Daylight Time (EDT), and so forth. Arizona, Puerto Rico, Hawaii, U.S. Virgin Islands and American Samoa do not observe Daylight Saving Time. Read more about the new federal law that took effect in March 2007 which extended Daylight Saving Time by four weeks.
