Traditional cities are based on most people working in the centre and living in a ring of suburbs, so journy patterns are radial.
Modern sprawl cities have no defined centre, so the transport patterns are far more random. Fewer people share the same routes. People in the east travel to the west to work, and people who live in the west travel to the east of the city. To support this transport pattern you need large multi-lane freeways between locations, so you have to spread locations out to leave room for the roads. People are using cars, like any other resource, to the point of inefficiency.
yeah, the U.S. will be increasingly facing major transportation issues... but because of numerous reasons i don't think will get better for a while:
* as stated above, most US cities (exceptions for older cities mostly on the East Coast) and are designed amlost exculsively for the automobile with sprawled homes and jobs and often very small percentage of businesses downtown
* the cheap gas and lack of good public transit perpetuates the cycle as people have few good options other than driving - so we put all money into auto infrastrcuture and don't "waste" money on public transit so it only get worse
* most Americans think "density" is a bad evil thing b/c they want thier big open land in the suburbs (of course it's just an illusion for most as they spend so much time in traffic)
although there are many great things about the automobile, as a basic transportation device for every person that has virtually replaced all other modes of transportation such as walking or public transit the negatives increase: pollution, people being injured and killed, traffic, etc... but the American people will effictively ignore the pollution and continue to happily waste energy and pave and pave and pave... but, some time soon (say 15-25 years) TRAFFIC will be so bad that the automobile will no longer be a viable solution for most people as it takes 2 hours or more to get to work or to school... i believe once a city or region reaches this "critical mass" point, solutions such as some new form of public transit or mass telecommuting or whatever will be developed very quickly... (assuming we can handle the costs)
until we get to this point, raising the gas price (or at least not heavily subsidizing the auto system) would help to moderate the damage of "designing for cars" and make it easier for when this day eventually arrives... as well as helping to reduce the pollution and environmental damage or driving SO many miles and paving so much of the U.S. land
of course there is also a danger that we have some kind of energy crisis (say an oil supply disruption from war or terrorism) in which case the U.S. would be in a bad position b/c our entire economy depends so heavily on oil: how can companies transport thier goods and people get to work w/o oil?
with all the conservative types in the U.S. worried about the threats to the U.S. and the economy it baffles me that we continue to allow this weakness to increase -- and just holding more oil in the reserves is a VERY short-term solution -- what if the oil supply were limited for 6 months? and with even a slight shortage oil prices would skyrocket as demand would continue to be high as almost everyone is SO dependent on oil...
given the past of things like flying 2 planes into the World Trade Center, i don't think it's too unlikely that terrorists could SERIOUSLY distrupt the planet's oil supply - not for days, but for months - by destroying numerous pipelines, ships and oils fields...
but the average American doesn't want to do ANYTHING to reduce his God-given right to drive his huge multi-thousand pounds of steel to wherever he wants and get free parking... pay more for gas! "waste" money on public transit! ride a bike!
there are many solutions that could greatly help, but [vitually] no one wants to...