A Nashville client and a Knoxville client share a state but live an hour apart. Thirteen US states straddle two time zones. Knowing which part falls where saves missed meetings, late flights, and confused colleagues.
The full list: Florida, Indiana, Kentucky, Tennessee, Michigan, Kansas, Nebraska, North Dakota, South Dakota, Texas, Idaho, Oregon, and Alaska. Each has a boundary line running through it, dividing the state into two different local times.
Why state lines and time lines don’t match
Time zone boundaries follow county lines, not state lines. When the US railroad system adopted standard time zones on 18 November 1883, the goal was practical: keep communities with close economic ties on the same clock. Boundaries were drawn along railroad routes, rivers, and population centers.
Over the decades, the Department of Transportation (DOT) has adjusted these lines. Counties have switched zones to align with nearby cities or economic partners. The result is that some states end up with two zones, sometimes awkwardly so.
Eastern, Central split states
Five states split between Eastern Time (ET) and Central Time (CT).
Florida is the most dramatic case. The Apalachicola River forms the boundary. Everything east of the river, including Jacksonville, Miami, and Orlando, is on Eastern Time. West of the river, the Florida Panhandle including Pensacola and Panama City runs on Central Time. Gulf County is split right down the middle, with the county seat, Port St. Joe, on Eastern Time while the western part of the county is on Central.
Indiana had one of the most complicated time histories in America. Before 2006, the state was a patchwork: most counties didn’t observe daylight saving time, and some were on Central while others were on Eastern. That year, the state standardized. Today, most of Indiana is on Eastern Time and observes DST. The northwest corner near Chicago (Lake, Porter, LaPorte, Newton, Jasper counties) and the southwest corner near Evansville (Gibson, Posey, Vanderburgh, Warrick counties) are on Central Time.
Kentucky splits down a diagonal line. The western half, including Bowling Green and Owensboro, is on Central Time. The eastern half, including Louisville and Lexington, is on Eastern Time.
Tennessee is similar. Most of the state, including Nashville and Knoxville, is on Central Time. But the eastern third, including Chattanooga and the Tri-Cities area, runs on Eastern Time.
Michigan has a small split. The Upper Peninsula’s western counties (Gogebic, Iron, Dickinson, Menominee) are on Central Time. The rest of the state, including Detroit and the Lower Peninsula, is on Eastern Time.
Central, Mountain split states
Five states split between Central Time (CT) and Mountain Time (MT).
Kansas has a tiny Mountain Time sliver. Four counties in the far west (Sherman, Wallace, Greeley, and Hamilton) run on Mountain Time. The rest of the state is on Central Time.
Nebraska splits along the Sandhills. The western third, including Scottsbluff and Chadron, is on Mountain Time. The eastern two-thirds, including Omaha and Lincoln, is on Central Time.
North Dakota has a small Mountain Time corner in the southwest. Mercer County moved from Mountain to Central in 2010, leaving only Bowman, Slope, Hettinger, and Adams counties on Mountain Time. The rest of the state is Central.
South Dakota splits along the Missouri River. The western half, including Rapid City and the Black Hills, is on Mountain Time. The eastern half, including Sioux Falls, is on Central Time.
Texas has a Mountain Time sliver in the far west. El Paso, Hudspeth, and part of Culberson County run on Mountain Time. The rest of the state is on Central Time.
Mountain, Pacific split states
Two states split between Mountain Time (MT) and Pacific Time (PT).
Idaho has a clear north-south split. The northern panhandle, including Coeur d’Alene, is on Pacific Time. The rest of the state, including Boise and Sun Valley, is on Mountain Time.
Oregon has a small Mountain Time corner. Malheur County in the far east, including Ontario, runs on Mountain Time to align with Idaho’s Treasure Valley. The rest of Oregon is on Pacific Time.
Alaska’s two time zones
Alaska is a special case. The state was originally divided into four time zones. In 1983, it consolidated to two. Most of Alaska is on Alaska Time (AKT, UTC-9). But the Aleutian Islands west of the line running through the archipelago, including Adak, run on Hawaii-Aleutian Time (HT, UTC-10). Hawaii itself is on Hawaii-Aleutian Time year-round, and it doesn’t observe daylight saving time.
How split-state boundaries affect daily life
Living in a split state means staying aware of the line. Broadcast networks use the “8/7 Central” system because live feeds air at different times across the country. A show that airs at 8 PM Eastern airs at 7 PM Central, but the network still promotes it as “8/7 Central” for the Mountain and Pacific feeds.
Businesses in border towns often post both times. Banks may have different hours depending on which side of the line they’re on. Schools and government offices set their schedules based on local time, which can cause confusion for families crossing the line for work or school.
Remote workers face the biggest challenge. A 9 AM meeting in Eastern Time is 8 AM Central, 7 AM Mountain, and 6 AM Pacific. If you’re scheduling across a split state, specify which zone you mean.
Can counties change their time zone?
Yes, and it happens more often than expected. The Department of Transportation has authority over time zone boundaries under federal law. Counties can petition the DOT to move to a different zone. The DOT holds public hearings and reviews economic and social impacts before deciding.
Recent examples include Mercer County, North Dakota, which moved from Mountain to Central in 2010 to align with the rest of the state. Some Indiana counties shifted in 2007 after the state standardized. In 2018, the DOT received petitions from several Texas counties near the New Mexico border to switch to Mountain Time, though none succeeded.
The process takes time. Petitions require evidence of economic ties, commuting patterns, and community sentiment. The DOT doesn’t change boundaries lightly, but it does change them.