Who regulates time zones? What is their history?
Time zones are regulated by the U.S. Department of Transportation and not NIST as commonly believed. Time zones originally were controlled by the Interstate Commerce Commission because the need for time zones came about when railroads were first used for interstate commerce. The United States was first divided into four time zones (Eastern, Central, Mountain and Pacific) on Nov. 18, 1883. In 1967, a congressional act transferred the duties of the ICC to the DOT. It is interesting to note that the DOT (and not NIST) is also responsible for the rules governing Daylight Saving Time.