The halfway point between Monticello, IA and Springfield, MO falls in or around Perry, Missouri.
Marshall, AR
Indiana
Durant, OK
Wyandotte MO
Dota, Arkansas.
Looking on Google Maps, I'd say Clarksville was about the halfway mark.
Mt Vernon, MO and Springfield, MO
Velarde, NM is the halfway point.
The town that is roughly halfway between Springfield, MO, and St. Louis, MO, along Interstate 44 is Rolla, MO. Located about 90 miles from both cities, Rolla serves as a convenient stop for travelers on this route. It is known for its historic downtown area and the nearby Missouri University of Science and Technology.
Greenville SC is about halfway from Florence SC to Cleveland TN.
What is the halfway point between Omaha NE and Springfield IL