In the Billings, MT area, we have two repeaters linked together; one on Red Lodge mountain (147.360), and one on top of the Bull Mountains (145.410) near Roundup. Both require 100 Hz sub-audible tone for access.
These two repeaters give us a coverage area from Worland, WY to Harlowton, MT and from Big Timber, MT to Custer, MT., and in some cases even further.
Wyoming has a repeater link-up that gives them nearly statewide coverage.
I once drove a Jeep from Billings, MT to Hanford, CA. monitoring 146.520 (the national calling frequency) all the way, and announcing my presence every 100 miles or so. I got one contact near Selma, CA.
At that time, I also had a CB in the Jeep. I monitored CH. 19 all the way, and made several contacts.
I have a 2 meter radio (Yaesu Ft-2900R) in the Jeep I now have. If I can find a place for it, I just might install a CB in it as well. I should, since I have 5 of them in a drawer in the garage!