[VoiceOps] where to find available dark fiber maps and info

I'm presently looking into the feasibility of bringing connectivity and bandwidth into undeserved rural markets and looking for places where dark fiber may already be accessable and available. Thus far in speaking with carriers it seems many if not most of them do not want to bother breaking into / breaking out unused dark fiber on their routes and only seem to know of their own routes but not the routes of others. Wheonsultingre can I find maps and such of where dark fiber exists, and who to negotiate with for it's use. I'm looking at / for both long haul routes that would give access into major NAPs & MAEs but also fiber laid around various (rural) towns and for instance between various tandems. Thanks, Eric Fort FortConsulting