If we're talking about population density in rural areas, then the poor countries of Africa (excluding Saharan desert) have a much higher rural population densi

If we're talking about population density in rural areas, then the poor countries of Africa (excluding Saharan desert) have a much higher rural population density than middle of USA, and there rolling out cell coverage is quite feasible, definitely more feasible than rolling out an electricity grid - there's already something like a hundred million people in sub-Saharan Africa who don't have electricity connections but do have mobile phones and coverage.