There are 13 states that have more than one time-zone.
The United States is a large country covering an area of 3,796,742 square miles. For the convenience of travelers and for economic, social, and commercial purposes the country has been divided into 11 time-zones. The states, Washington D.C., and the overseas territories follow these time zones. Of the 50 states, 37 are contained within one time-zone. However, there are 13 states that use more than one time-zone.
The states that observe more than one time-zone are Oregon, Idaho, Nebraska, Kansas, Texas, North Dakota, South Dakota, Florida, Michigan, Indiana, Kentucky, Tennessee, and Alaska. Among these Alaska is the only state that is not part of contiguous United States. The causes for these states to observe multiple time zones range from geographic, socio-political, to economic.
Most of Alaska observes the Alaska Standard Time, the Aleutian Islands use the Hawaii-Aleutian Standard Time. Most of Oregon follows the Pacific Standard Time, but around 80 percent of the northern part of the Malheur County uses the Mountain Standard Time.
Mountain Standard Time is used in most of Idaho, while some parts use the Pacific Standard Time. The Central Standard Time is observed in North Dakota. The Mountain Standard Time is used in the west of the Missouri River, excluding Oliver and Morton counties and a few parts of McKenzie, Dunn, and Sioux counties. The eastern part of South Dakota uses the Central Standard Time, while the western half observes the Mountain Standard Time.
Texas follows the Central Standard Time, except for El Paso and Hudspeth counties which follow the Mountain Standard Time. In Florida, some parts observe the Eastern Standard Time, while others the Central Standard Time. The two time-zones used in Kentucky are the Eastern Standard Time and Central Standard Time.
Kansas uses the Central Standard Time, except the counties of Greeley, Hamilton, Sherman and Wallace, which observe the Mountain Standard Time. The Eastern Standard Time is observed in Michigan, but the Central Standard Time is observed in the counties in Upper Peninsula that border Wisconsin. Most of Nebraska observes Central Standard Time, while a few parts follow Mountain Standard Time.
While most of Indiana uses Eastern Standard Time, the northwest and southwest corners observe the Central Standard Time. The Central Standard Time and the Eastern Standard Time are observed in Tennessee.