There's only more cars if there are more jobs, at least if you're looking at rush hour traffic. Adding residences in megacities like LA and SF isn't likely to i

There's only more cars if there are more jobs, at least if you're looking at rush hour traffic. Adding residences in megacities like LA and SF isn't likely to increase the number of jobs, it will reduce the number of people commuting 30+ miles into the city, and thereby reduce the number of cars on the road (even if everyone still drives.)