Reference:

http://www.mapsofworld.com/usa/thematic-maps/usa-time-zone.html

http://www.time.gov/

USA Time Zone Map represents the different time zones of the United States of America. USA is divided into six standard time zones. A seventh time zone of the US covers the US Virgin Island and Puerto Rico region. Most of the US States observe daylight saving time for maintaining uniformity of time in certain areas. All these aspects can be learned through a detailed study of United States Time Zone Map.

There are two federal time agencies operating in the US, the Department of Commerce Agency, the National Institute of Standards and Technology, and its military counterpart the United States Naval Observatory, which is a defense organization. These agencies provide accurate time of every region of the US.

The USA time zone map given on this page defines the time zone boundaries in the US, which are under the authority of Department of Transportation along with the Daylight Saving Time observances. From Time Zone in the United States chart and USA time zone clock, one can learn about the principal time zones in the US, which are as follows: EST or Eastern Standard Time Zone, which includes the states on Atlantic coast and eastern portion of Ohio valley; CST or Central Standard Time Zone that covers the Gulf coast, Tennessee Valley and Great Plains; MST or Mountain Standard Time Zone, which includes the Rocky Mountains; PST or Pacific Standard Time Zone that covers the states on the Pacific coast including Nevada. Time Zones in the non-contiguous states of US are Alaska Standard Time Zone or AKST and Hawaii-Aleutian Standard Time Zone or HAST. All of the Standard time zones are defined in terms of offsets from UTC or Coordinated Universal Time.