US Time Zones

The United States covers several time zones because of which, time changes, such as Daylight Saving Time, happen differently in some areas, such as Arizona, where it’s not observed, making time keeping varied across the country.

How Many Time Zones in USA?

The United States has nine standard time zones ranging from the Eastern Time Zone with big cities like New York and Washington D.C., to the Chamorro Standard Time in Guam and the Northern Mariana Islands in the Pacific. This variety helps match the local times to the natural daylight of each area across the U.S. and its territories.

Time Zones in USA

• Atlantic Standard Time (AST)

  This time zone is mainly used in Puerto Rico and the U.S. Virgin Islands, which are located in the Caribbean.

  AST does not change for Daylight Saving Time, so the time stays the same all year. This keeps the islands on a similar schedule to many nearby Caribbean places. The UTC offset of AST is 4 hours.

• Eastern Standard Time (EST)

  This time zone covers Connecticut, Delaware, parts of Florida, Georgia, parts of Indiana, parts of Kentucky, Maine, Maryland, Massachusetts, parts of Michigan, New Hampshire, New Jersey, New York, North Carolina, Ohio, Pennsylvania, Rhode Island, South Carolina, parts of Tennessee, Vermont, Virginia, West Virginia.

  EST is the time zone used on the busy East Coast, including big cities like New York City, Boston, and Washington D.C. When Daylight Saving Time starts, the clocks are set ahead by one hour, changing EST to Eastern Daylight Time (EDT). The UTC offset of EST is 5 hours.

• Central Standard Time (CST)

  This time zone covers Alabama, Arkansas, parts of Florida, Illinois, parts of Indiana, parts of Iowa, Kansas, parts of Kentucky, Louisiana, parts of Michigan, Minnesota, Mississippi, Missouri, Nebraska, parts of North Dakota, Oklahoma, parts of South Dakota, parts of Tennessee, Texas, Wisconsin.

  CST covers the central region of the country, including cities like Chicago, Dallas, and New Orleans. During Daylight Saving Time, it changes to Central Daylight Time (CDT). The UTC offset of CST is 6 hours.

• Mountain Standard Time (MST)

  MST covers Arizona, Colorado, parts of Idaho, parts of Kansas, Montana, parts of Nebraska, New Mexico, parts of North Dakota, parts of Oregon, parts of South Dakota, parts of Texas, Utah, Wyoming.

  This time zone covers the mountainous areas of the U.S. and includes cities like Denver and Salt Lake City. Most places change to Mountain Daylight Time (MDT) during Daylight Saving Time, but most of Arizona doesn’t follow this change and keeps the same time all year. The UTC offset of MST is 7 hours.

• Pacific Standard Time (PST)

  It covers California, parts of Idaho, Nevada, Oregon, Washington.

  PST is the time zone for the entire West Coast of the U.S., including cities like Los Angeles, San Francisco, and Seattle. It follows Daylight Saving Time, switching to Pacific Daylight Time (PDT) during those months. The UTC offset of PST is 8 hours.

• Alaska Standard Time (AKST)

  This time zone is used in most of Alaska. During Daylight Saving Time, it changes to Alaska Daylight Time (ADT). This adjustment helps manage the large size of Alaska and its different amounts of daylight throughout the year. The UTC offset of AKST is 9 hours.

• Hawaii-Aleutian Standard Time (HST)

  It covers Hawaii and the Aleutian Islands (part of Alaska).

  HST does not change for Daylight Saving Time, so the time stays the same all year. This makes the island’s time quite different from the time on the mainland U.S. The UTC offset of HST is 10 hours.

• Samoa Standard Time

  This time zone includes American Samoa, keeping it one hour behind the neighboring independent state of Samoa. It does not observe Daylight Saving Time. The UTC offset of Samoa Standard Time is 11 hours.

• Chamorro Standard Time

  This time zone is used in Guam and the Northern Mariana Islands in the western Pacific and does not change for Daylight Saving Time. It is similar to time zones in Asia, which helps these islands interact more easily with nearby areas. The UTC offset of Chamorro Standard Time is 10 hours.

Interesting Facts

• The concept of time zones was first suggested by Sir Sandford Fleming, a Canadian railway planner and engineer, in the late 1800s. He proposed it as a way to fix the confusion caused by different local times in various cities.
• Arizona is unique among the states because it does not observe Daylight Saving Time (DST), with the exception of the Navajo Nation, which does. This means that Arizona’s clocks do not change in spring and fall, unlike most of the rest of the country.
• Until 2006, Indiana had a complicated relationship with DST, with some counties observing it and others not. Now, the entire state observes DST, but it is split between Eastern and Central time zones.
• Oregon and Idaho are each divided into two time zones: Pacific and Mountain. This division can lead to interesting situations for travel and media broadcasts within these states.
• In Barrow, Alaska, the sun stays up and doesn’t set at all for 60 days during the summer. In contrast, during the winter, the sun doesn’t rise for 60 days straight. This extreme change in daylight affects how locals experience time.

Related Links

• Key Facts of USA
• How Big is USA?
• Largest State in USA
• How Old is the United States?