The fair place to meet is Indianapolis, IN — the city closest to the midpoint of Chicago and Louisville. From the farther side that’s about 3 hr 27 min of driving.
Recommended midpoint
Indianapolis, IN
From Chicago
3 hr 27 min
165 mi to Indianapolis
From Louisville
2 hr 40 min
107 mi to Indianapolis
Louisville has the shorter trip; the split is off by about 47 min. The alternatives below can even it out. Chicago and Louisville are about 269 miles apart.
Chicago and Louisville are about 269 miles apart by road. Split the difference and you arrive near Indianapolis, the city closest to the halfway point between them. That puts roughly 3 hr 27 min of driving on the Chicago side and 2 hr 40 min on the Louisville side — the fairest single meeting point among the cities near the middle.
At this range, Indianapolis works for a same-day meetup: close enough from both Chicago and Louisville to meet for lunch or an afternoon and still be home by evening.
If Indianapolis doesn't have what you're after, Cincinnati and Columbus are also close to the midpoint and worth a look — each keeps the drive reasonably balanced between Chicago and Louisville.
Indianapolis, colloquially known as Indy, is the capital and most populous city of the U.S. state of Indiana and the county seat of Marion County. Indianapolis is situated in the state's central till plain region along the west fork of the White River. Read more →
Chicago is the most populous city in the U.S. state of Illinois and in the Midwestern United States. Located on the western shore of Lake Michigan, it is the third-most populous city in the United States, with a population of 2.74 million at the 2020 census. Read more →
Louisville is the most populous city in the U.S. state of Kentucky, sixth-most populous city in the Southeast, and the 27th-most-populous city in the United States. Read more →
City descriptions adapted from Wikipedia (CC BY-SA); photos via Wikimedia Commons, credited above.
Estimates use straight-line distance and typical road speeds; real drive times vary with route and traffic.