The United States of America and its surrounding areas use 9 standard time zones. Also, these abbreviations can be the same as those used in other parts of the world for different time zones. The shorter abbreviations we often use are just for convenience and are not official. The official names of the time zones are what's used in laws and official documents. Before this, they were based on the solar time at different longitudes west of Greenwich, UK. Since August 9, 2007, these time zones are defined by how many hours they are ahead of or behind Coordinated Universal Time (UTC). The Secretary of Transportation has the power to decide which time zones different regions will use and whether they'll follow daylight saving time. This law decides when daylight saving time starts and ends, if it's used. In the United States, standard time zones and the rules for daylight saving time are set by federal law (15 USC §260). United States Maps in our Store - Order High Resolution Vector and Raster Files It is the mix of the time zone and DST rules, along with the timekeeping services, which calculate the legal civil time for any United States location at any moment.

The clocks managed by these services are kept in synchronization with each other as well as with those of other internationally recognized timekeeping organizations. Official and extremely precise timekeeping services (clocks) are presented by 2 federal agencies: NIST (the National Institute of Standards and Technology) (an agency of the Department of Commerce) and UNSO (the United States Naval Observatory). The time zone boundaries and daylight saving time observance are organized by the Department of Transportation. observing DST (daylight saving time) for generally the spring, summer, and fall months. Explore US time zone map, Time in the United States of America, by law, is divided into 9 standard time zones covering the American states, territories and other U.S.

International time zone map