Interstate 35, Guthrie, OK 73044.
Kirk, Colorado is halfway between Amarillo & Rapid City
Amarillo, TX
Concordia, Kansas is the city that is halfway.
One big city that is halfway between California and Ohio is Amarillo, TX. Another is Oklahoma City, Oklahoma. Not as big but almost exactly halfway is Elk City, Oklahoma.
Huntington, GA
According to mapquest it is 612 miles.
maps.google.com Kansas City, Kansas or Wichita, Kansas
What city is Halfway between Goodland, Kansas and Ontario, Canada
Pigeye, Alabama is the halfway point (yes, really).
No city is exactly halfway between, but Lawrence in the closest. ROCK CHALK!
The halfway point is basically the area where Nebraska, Colorado and Wyoming meet. This is not an exact answer, but in relative terms this is the halfway point between Salmon, Idaho and Kansas City, Missouri. If your looking for a town, then I would say the capitol city of Wyoming (Cheyenne) is pretty much as close as your going to get to a city halfway between Salmon and K.C.
Kansas City, Missouri.