Low population areas generate less traffic and less pollution. Let them be, for now. Focus on the 80%. Also, in-settlement transport is the US problem. It's p

Low population areas generate less traffic and less pollution. Let them be, for now. Focus on the 80%. Also, in-settlement transport is the US problem. It's probably fine if a lot of inter-settlement transport remains by car, except for connections between cities of say, more than 200k that are closer than 300km from each other.