At least 14 US states have a Harrisburg, including two in Ohio alone. Since the most famous one is in Pennsylvania, I'll give you St. Louis as the halfway point. If you meant one of the others, please re-submit your question with more information.
Toledo?
The halfway point between Hanover, MD and Toledo, Ohio falls in or around Indianola, PA.
The halfway point is in Raphine, VA.
Toledo
Hagerstown
Indiana
The halfway point between Pelham Drive, Fort Wayne Indiana, and Toledo, Ohio falls in or around Defiance, Ohio. There is no city of Pelham.
Lexington, VA
Martinsburg, Maryland.
Falmouth, VA
Ripley, WV
Caledonia, IL