 Map of U.S. time zones since November 2007
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In the United States, time is divided into nine standard time zones covering the states, territories and other US possessions, with most of the country observing daylight saving time (DST) for approximately the spring, summer, and fall months. The time zone boundaries and DST observance are regulated by the Department of Transportation, but no single map of those existed until the agency announced intentions to make one in September 2022.[1] Official and highly precise timekeeping services (clocks) are provided by two federal agencies: the National Institute of Standards and Technology (NIST) (an agency of the Department of Commerce); and the United States Naval Observatory (USNO). The clocks run by these services are kept synchronized with each other as well as with those of other international timekeeping organizations.
It is the combination of the time zone and daylight saving rules, along with the timekeeping services, which determines the legal civil time for any U.S. location at any moment.
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- ^ Wallace, Gregory (September 22, 2022). "DOT to map out nation's time zones after report shows no official map exists". CNN. Retrieved September 27, 2022.