There are four time zones in the continental United States: Eastern, Central, Mountain and Pacific. Alaska and Hawaii have their own time zones: Alaska and Hawaii-Aleutian. U.S. territories use three additional time zones: Atlantic, Samoa and Chamorro.
Most states are wholly contained within a single time zone. A total of 15 states fall into two different time zones, including Alaska, Michigan, Indiana, Tennessee, and Kentucky. As of 2015, all states observe daylight savings time except for Arizona and Hawaii.
Native American tribes have the authority to designate time zones and daylight savings time observance in their tribal lands. The Navajo Nation observes daylight savings time, despite being located in Arizona. Conversely, the Hopi Nation is located entirely within the Navajo Nation but does not observe daylight savings time.