There are substantial areas in Wyoming where ATT and Verizon don't even have voice coverage (I guess neither do Sprint or TMobile, but I didn't check those 2). ATT maps pretty much the entire coverage of Wyoming as third party.
I think it is impossible to calculate with publicly available data, but the interesting statistics would compare the networks directly in terms of infrastructure costs for new coverage (perhaps divided over the number of new customers in that coverage, but coverage has, uh, network effects) and infrastructure costs being spent on enhancing service levels in already covered areas.
More: Presumably, higher costs to add coverage to new people would indicate more complete coverage. The presumption being that a business is investing in the more profitable coverages first, so the later areas have a higher cost per customer accessed.
I think it is impossible to calculate with publicly available data, but the interesting statistics would compare the networks directly in terms of infrastructure costs for new coverage (perhaps divided over the number of new customers in that coverage, but coverage has, uh, network effects) and infrastructure costs being spent on enhancing service levels in already covered areas.
More: Presumably, higher costs to add coverage to new people would indicate more complete coverage. The presumption being that a business is investing in the more profitable coverages first, so the later areas have a higher cost per customer accessed.