Everyone talking about the highways DOES know some of the back story I hope on why they came to be. Recall the highway act was passed during the Eisenhower Administration in 1956. Remember Ike's former job? Yes, Supreme Commander of Allied armies in Europe, ~43-45. He saw the military value of the Autobahn up close and personal and was also part of a 1919 coast to coast convoy experiment for the Army.
http://en.wikipedia.org/wiki/Federal_Aid_Highway_Act_of_1956Eisenhower debated for the highways for the purpose of national defense. In the event of a ground invasion by a foreign power, the U.S. Army would need good highways to be able to transport troops across the country efficiently. Following completion of the highways the cross-country journey that took the convoy [that Ike participated in as a junior officer] two months in 1919 was cut down to two weeks.
There was also another consideration in suburbanization in the 1950's.
http://en.wikipedia.org/wiki/Ivy_mikeSmall, dense cities holding most of the population resulted in a small target set for an attack to wipe the population. At that time, in the 50's, bombs were so large [even the atomic, in lieu of hydrogen] that bombers could typically carry only 1, which would be used on the city core. Pre hydrogen bomb, if you were more than about 5 miles from the city core, you'd probably survive since the yields and damage radi were quite modest for a 100kt fission bomb [in nuke bomb terms, of course], versus the multi-megaton hydrogen bombs that followed in the late 50's and early 60's.
Notice how on the flat lands between the Rockies and East coast how there are ring (or "collar" as noted in previous posts) highways
around many cities at 5 to 10 miles from the (then) city center? Yup.....figured that the commies would nuke the city core, but a ring highway would be far enough out to still be passable to military convoys. They were originally nothing about suburb to suburb transportation. It was so you wouldn't have to drive through a radioactive crater where the previous east-west and north-south highways crossed.
Russians popped their first true "big one" November of 55.
http://en.wikipedia.org/wiki/Nuclear_arms_raceDo you think this might have influenced folks a wee bit? Perhaps, considering the timing of the year before the highway act was passed.
And then the miniaturization of warheads, ICBM's, then MIRVed ICBM's, SLBM's, MIRVed SLBM's, cruise missiles, etc and the now obvious silly premise of a land invasion of the US makes the original rationale for the highways and ring highways kind of silly. Heck, with (the commie equal of) something like this:
http://en.wikipedia.org/wiki/UGM-73_PoseidonYou'd scatter the 10 to 14 warheads over an entire city area - hitting every major road junction (5 for a ring plus N-S / E-W), 3 into the city core, and scatter the rest around the 'burbs.
Another underlying tension leading to the highways was the populations disgust with the passenger railroads and the as yet not developed modern airline system. Read some railroad history books about the time for the back story there. After crappy service in the 30's, the war years in the 40's with packed and dilapidated pax trains, and continuing high prices and crappy service in the 50's, people wanted to NOT be dependent on shitty service to get from city to city - they preferred to drive themselves. This, combined with the highways, certainly influenced the blooming car culture in the 50's and 60's - "the freedom of the open road". And since you had the car already, why not have the nice new, modern suburban house, lawn, said car in the driveway and a charcoal grill on the patio?