[swatcoder]

Those northeast cities form a connected industrial corridor that specifically bloomed during the train age. People and goods were actively shuffling around between them and within them as the very essence of why they existed.

Meanwhile, many other US cities were developed around regional agriculture, ranching, frontier settlement, and/or sea and river ports. Some explored sophisticated public transit systems at one point or another, but by the time they got really urbanized, cars were widely available and it was easier to justify roads and highways for personally-owned vehies than far more expensive train/tram infrastructure. We now see how car-centrism introduces limits on growth, but there wasn't a consensus sense of what those limits were or whether growth would really encounter them.

[tsimionescu]

You also shouldn't forget that car companies actively bought and dismantled mass transportation in several of those cities, at a loss to them, for the express purpose of driving demand for cars.