Accurate to within 1 second. Pick a time zone in the the United States or its territories. The official U.S. government time is displayed in large, easy-to-read numerals, along with the coordinated universal time and a world map displaying where the sun is shining. "Time Exhibits" provides information about daylight-saving time, calendars, clocks, watches, timekeeping, and more. From the National Institute of Standards and Technology (NIST)and the U.S. Naval Observatory (USNO).