The letter "o."
the city is catnipp
Mt Vernon, IL
Loring, Iowa.
The halfway point is just west of Iowa City, Iowa.
The halfway point between Mt. Pleasant, Iowa, and Branson, Missouri, is about halfway between Fulton and Jefferson City, Missouri.
Liberal, KS
Cincinnati, OH
West Des Moines, Iowa
Richmond, Indiana is close to halfway.
North English, Iowa is halfway between Evansville & Watertown
Smeltertown, Colorado is exactly halfway. You could try Denver if you want a bigger city.