I haven't actually been to Montana a lot—I'm saving much of it to explore later. Covering Montana anyway here was made possible by using Bedavd's ATS IRL Map, which is basically an overlay to Google Maps. As a result, some details in the descriptions of Montana cities won't be quite accurate in the C/FD. These inaccuracies are caused by my use of the map, not by Bedavd. For example, a street may be named "First Street" on Google Maps, but without checking it out in ATS myself, I have no way of knowing whether SCS put a sign into the game that actually says "First Street". Usually I just have to assume that they did.
I don't believe this is much of a problem. In most cases, having some information available will be much better than having none at all.
The cities I haven't been to yet myself are clearly marked on the C/FD status overview map as well as in the C/FD itself. I use the term "not field-checked" for this purpose.
Oklahoma cities are unaffected by the above. I have been to all of them.
I'm undecided about how to approach Kansas once it arrives. I'm leaning towards giving it the "Montana treatment"