Michigan and Kentucky both ended up split between Eastern and Central time — but they got there through almost opposite stories: one driven by a grassroots campaign for more evening sunlight, the other by a single city's decision that the rest of the state gradually followed.
Michigan: the "More Daylight Club"
All of Michigan used to run on Central Time. That started changing in 1907, when a Detroit group calling itself the More Daylight Club began campaigning for the city to move to Eastern Time instead. Their argument was almost entirely about quality of life: on Central Time, the sun was setting before 7pm even in summer, cutting into the after-work daylight hours people had to enjoy the "pleasant months of the year," as the club's founder George Renaud put it in a 1916 essay arguing for the change.
Detroit made the switch to Eastern Time in 1915. Over the following decades, the rest of the state gradually followed the same logic — by 1973, most of Michigan's Upper Peninsula had joined the switch too, leaving only four counties still on Central Time today: Gogebic, Iron, Dickinson, and Menominee, all in the western Upper Peninsula along the Wisconsin border, where economic ties to Wisconsin communities matter more than alignment with the rest of Michigan.
Kentucky: Louisville led, the rest of the east followed
Kentucky's story is less about daylight preference and more about one city's economic gravity. Louisville switched to Eastern Time in 1961, and the rest of eastern and northern Kentucky gradually followed suit in the years after. Today, roughly 60% of the state — including Louisville, Lexington, and Frankfort — runs on Eastern Time, while the western portion, including Bowling Green and Paducah, remains on Central.
The dividing line runs roughly northwest to southeast, west of Louisville, and doesn't follow any particularly obvious geographic feature — it largely reflects which parts of the state had stronger economic ties eastward toward Louisville and the Appalachian region versus westward toward Nashville and the broader Central Time South.
What both stories have in common
Neither state's split was created by a single federal decision — both emerged gradually, city by city and county by county, as local communities weighed their economic and social ties against straightforward geography. That's the same pattern behind most of the US's other split-state boundaries: the lines follow who a community actually does business and stays in sync with, not necessarily the shortest path across the map.
If you're scheduling with contacts in either state, don't assume: Detroit and Grand Rapids are Eastern, but the far western Upper Peninsula is Central; Louisville and Lexington are Eastern, but Bowling Green and Paducah are Central. The time zone converter resolves each by city, so neither state's internal split causes a mixup.
Frequently asked questions
Which Michigan counties are on Central Time?
Four — Gogebic, Iron, Dickinson and Menominee — all in the Upper Peninsula along the Wisconsin border, where economic ties to Wisconsin communities matter more than lining up with the rest of Michigan. Everywhere else in the state, including Detroit and Grand Rapids, runs on Eastern Time.
Why is Detroit on Eastern Time?
A quality-of-life campaign. From 1907 a Detroit group called the More Daylight Club pushed the city to move off Central Time, arguing that the sun was setting before 7pm even in summer and cutting into after-work daylight. Detroit made the switch to Eastern Time in 1915.
How much of Kentucky is on Eastern Time?
Roughly 60% of the state by land area, including Louisville, Lexington and Frankfort. The western portion, including Bowling Green and Paducah, stays on Central. The dividing line runs roughly northwest to southeast, west of Louisville, and does not follow any obvious geographic feature.
Why is Kentucky split between two time zones?
Economic gravity, not geography. Louisville switched to Eastern Time in 1961 and eastern and northern Kentucky gradually followed. The line reflects which parts of the state had stronger ties eastward toward Louisville and Appalachia versus westward toward Nashville and the broader Central Time South.