Why some states have two time zones
The US Department of Transportation draws the lines. The rule is local economic and social ties. A county that does business, commutes, and watches TV with a city in the neighboring state petitions to share that state’s time. The result: a jagged boundary that cuts through states, not around them.
Today roughly 15 states have territory in two zones. In almost every case the smaller portion is the exception. A handful of counties, sometimes only one, on the far side of the line.
The complete list of split states
| State | Zones | Which part is the exception |
|---|---|---|
| Florida | Eastern / Central | Panhandle west of the Apalachicola River is Central |
| Texas | Central / Mountain | El Paso and most of Hudspeth County are Mountain |
| Kansas | Central / Mountain | Four westernmost counties are Mountain |
| Nebraska | Central / Mountain | Panhandle around Scottsbluff is Mountain |
| South Dakota | Central / Mountain | Western half (Black Hills, Rapid City) is Mountain |
| North Dakota | Central / Mountain | Southwestern corner is Mountain |
| Kentucky | Eastern / Central | Western half is Central |
| Tennessee | Eastern / Central | Western half (Nashville, Memphis) is Central |
| Indiana | Eastern / Central | 12 counties near Chicago and Evansville are Central |
| Michigan | Eastern / Central | Four Upper Peninsula counties along Wisconsin border are Central |
| Idaho | Mountain / Pacific | Northern panhandle is Pacific |
| Oregon | Pacific / Mountain | Most of Malheur County is Mountain |
| Nevada | Pacific / Mountain | West Wendover is Mountain |
| Alaska | Alaska / Hawaii-Aleutian | Western Aleutian Islands are Hawaii-Aleutian |
Which part of Florida is on Central Time?
The line runs along the Apalachicola River. West of it, Pensacola, Panama City, and most of the panhandle sit in the Central zone. East of it, Tallahassee and the rest of the state use Eastern. The difference is one hour: when it is noon in Miami, it is 11:00 a.m. in Pensacola.
Where does Texas switch to Mountain Time?
Texas keeps Central statewide except for El Paso and most of Hudspeth County in the far west. Those two areas look toward New Mexico and use Mountain. El Paso is one hour behind Dallas.
Which Great Plains states split between Central and Mountain?
Each of these states keeps its major cities on Central and hands a thinly populated western edge to Mountain.
- Kansas: The four westernmost counties (Sherman, Thomas, Wallace, Greeley) are Mountain. The rest is Central.
- Nebraska: The panhandle counties around Scottsbluff are Mountain. Lincoln and Omaha are Central.
- South Dakota: Roughly the western half, including Rapid City and the Black Hills, is Mountain. Sioux Falls and the east are Central.
- North Dakota: The southwestern corner, around the town of Marmarth, is Mountain. Bismarck and Fargo are Central.
Where do Kentucky and Tennessee split between Eastern and Central?
These two states are the rare cases where the split is close to even in population. Both have long-running debates about unifying.
- Kentucky: The line runs roughly down the middle. Louisville and Lexington are Eastern. Bowling Green and Paducah are Central.
- Tennessee: East Tennessee (Knoxville, Chattanooga) is Eastern. Nashville and Memphis are Central.
How does Indiana handle its time zone boundary?
Indiana was a time zone mess until 2006. Before then, parts of the state observed daylight saving time and parts did not, and the boundary shifted county by county. Since 2006 the entire state observes DST, but 12 counties remain on Central: a cluster near Chicago in the northwest and a cluster near Evansville in the southwest. The rest of Indiana is Eastern.
For the full history, see Indiana Time Zone History.
Alaska: From four zones to two
Before 1983 Alaska had four time zones. That year the state consolidated to two: Alaska Time (most of the state) and Hawaii-Aleutian Time (the western Aleutian Islands only). The Aleutian portion does observe daylight saving time; Hawaii does not. This creates a split within the same named zone. See Alaska Time Zones for details.
Oregon and Idaho: Mountain Time on the border
- Oregon: Almost entirely Pacific. The exception is most of Malheur County in the far east, which uses Mountain because its economy is tied to Boise, Idaho.
- Idaho: The state is cut across the middle. The northern panhandle above the Salmon River keeps Pacific, aligning with Spokane, Washington. Boise and southern Idaho keep Mountain.
- Nevada: Almost entirely Pacific. The small town of West Wendover on the Utah line uses Mountain so it can share a clock with Salt Lake City.
How do I schedule a call when a state has two time zones?
The default advice for scheduling across US time zones is “use Eastern for everything.” That works if you are calling New York from Los Angeles. It fails when the person you are calling lives in the Florida panhandle (Central), western Kentucky (Central), or El Paso (Mountain). Anyone scheduling with a contact in a split state should ignore the default. Check the county. If you do not know the county, ask the person what time zone their address uses. Their TV listings and commute will tell you the truth.