Forsyth, MT
K
Pendleton, Oregon, seems to be about halfway between Boise and Tacoma. The Tri-Cities are nearby the halfway point, and they are a larger metro area.
Monticello, UT
North Hartland, NY is the halfway point.
Fairfax, MO
La Grande, OR
Price, UT
davenport
The halfway point is Gandy, UT.
Roanoke Rapids, NC
Boise, Texas
According to Meetways.com, the halfway point between Boise, Idaho and Sioux Falls, South Dakota would be on US Highway 14 in the Bighorn National Forest near Dayton, Wyoming.