The New York Times has a very interesting article about where americans put their money, and how their spending habits change during the time (the graph is in fact drawn from the Consumer Price Index, one of the possible measures of inflation).
The graph by itself is quite self-explanatory. My comment is below.
Housing is 42% of spending, transportation is 18%. Together they form 60% of US spending. It means that cities of the future (ecologic, efficient, cost-effective) can be the only way for the U.S. to stay on top of the world economy.
My opinion about big cities is: they are incredibly efficient, compared to rural towns, but yet there is lots of room for improvement, both in transportation (which must be only public inside cities, renting cars when you have to go outside) and housing (they must be industrialized like ford T model, but also customizable to meet the client’s request).
If you’re not convinced that taking care of the environment is a good idea, read what Tim O’Reilly has to say about Fermi’s Paradox.