The United States is a vast country covering an area of 3,796,742 square miles. For the convenience of travelers and economic, social, and commercial purposes, the country has been divided into 11 time zones. The states, Washington DC, and the overseas territories follow these time zones. Of the 50 states, 37 are contained within a one-time zone. However, 13 states 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 the contiguous United States. The causes for these states to observe multiple time zones range from geographic, socio-political, to economic reasons.
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 Malheur County uses the Mountain Standard Time.
Mountain Standard Time is used in most of Idaho while some parts use Pacific Standard Time and 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 Central Standard Time, while the western half observes Mountain Standard Time.
Texas follows Central Standard Time, except for El Paso and Hudspeth counties which follow Mountain Standard Time. In Florida, some parts observe Eastern Standard Time, while others the Central Standard Time. The two time zones used in Kentucky are Eastern Standard Time and Central Standard Time.
Kansas uses Central Standard Time, except for 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 has 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.