West Frankfort, IL
Bettendorf, IA but anywhere in the Quad Cities would be fine.
Miner, MO is the halfway point. That's a little past Cape Girardeau. Paducah is nearby, but not on the way. As it's only a four-hour trip, there's not a big city in between.
Effingham, IL is about halfway between these two cities.
There is approximately 748 miles between Madison, Wisconsin and Rochester, New York. The halfway point between these two cities is Toledo, Ohio.
I-40 and I-20 are essentially the same time. I-40 - Jackson, TN is halfway (though you could stop in Memphis or Nashville if looking for larger cities) I-20 - middle of nowhere AL is halfway...though Tuscaloosa, AL or Meridian, MS are the largest cities/towns around the halfway mark. If you're looking for a city then shoot for Jackson, MS or Birmingham, AL.
If you're driving (and take the fastest route) it would be St. Clairsville and Wheeling in Ohio and Washington in Pennsylvania. If the distance is direct it would be Parkersburg, West Virginia.
The line 90 degrees west longitude, which includes the cities of New Orleans LA and Memphis TN.
Indianapolis, IA Indianapolis, IN and Indianapolis, OK
There is a category on this website for "Halfway Points." You can also find the distance between two of your cities and divide it in two. The distance between Philadelphia and Chicago is 760 miles. The halfway point is 380 miles.
Chattanooga and Memphis are major cities in Tennessee, USA.
Depending on the cities you start and end at , somewhere in southern Kansas or northern Oklahoma
The city that is halfway between Miami, FL and Charleston, SC is Cedar Landing, FL. It is the exact halfway point between the two cities.