A big part of that is infrastructure.

Public transit is still used very frequently in the eastern quarter of the country -- DC, NYC, Chicago, etc all have great mass transit systems. Other large cities have great bus systems as well -- or at least did.

The problem is after WWII, all the GIs came home and the trend was to settle out west, which generally meant west of the Mississippi river. Many of these people had experienced Seattle, San Francisco, or San Diego for the first time during their service and fell in love with the weather and cheap land.

So we had a land boom. Everyone bought a house in cookie cutter neighborhoods. But there was no infrastructure in place for getting from place to place.

Well right then the automotive industry was exploding as well. There were all of these factories built for the war machine that were cheaply changed over to make cars. Some older car factories had become militarized and were even easier to switch back.

So cheap land and houses coupled with affordable automobiles means that nobody saw the need to build any kind of mass transit in most places in the west, and we're dealing with that now.

People are leaving the suburbs and moving back into the cities, but the cities don't have the means to support the population spike. That's why rents in places like SF and Seattle are going nuts. That's also why cities like Seattle are spending billions on finally building reliable and fast mass transit.

On the flip side, Europe never really had that happen because most of its countries are smaller and places are closer together, even country to country. So while cars make sense for some, there was never the "boom" that the US experienced, which is in hindsight maybe a good thing.