In retrospect it's easy to see areas where this growth could have happened in better fashion. There was certainly for a time a concerted effort on the part of automobile manufacturers and oil interests to kill public transportation. But even that is a bit of a double edged sword, as these industries were a substantial factor in the growth of the economy and the creation of a large middle class. This doesn't justify the planning errors resultant from influences of this cabal, but it does offset at least in part whatever economic detriments stemmed from them.
That era of growth is now seemingly on a downward slide as the advantages once enjoyed over the rest of the world have begun to disappear. Whether or not the use of automobiles is sustainable, the economic boom they once provided certainly is not. But absent a total economic collapse, I don't see us ever returning to a world of carts, trolleys and bicycles as the dominant forms of transportation. New energy sources will arise and other forms of transit will be developed, but transportation will remain substantially mechanized. I enjoy the notion of returning to a simpler time, but I honestly don't wish to live to see that as I think it would come only as a result of economic devastation so severe that our world would be a pretty grim place for quite a long time.