So this is not as black and white as it seems. There are three major pushes that end up pushing people out of the cities.
* the aforementioned highway boom, but this is not enough to actually kickstart the whole thing; most European nations also had a highway boom around this time with much less sprawl
* lending standards. Prior to the Great Depression, banks are wholly in control of mortgage lending. The collapse of the economy also collapses the banking system and the housing market; banks have to foreclose on properties that are no longer worth anything. As part of the bank stabilization efforts, the FHA creates national standards for loans that it will insure. These standards are restricted to single family homes, and to properties without commercial (small businesses have a really high rate of failure). This has the effect of encouraging banks and developers to stampede into single family suburban development; the cost of financing is a lot cheaper because of the Uncle Sam guarantee, and it's a lot more profitable as a result. No other type of property is given this kind of preferential treatment to this extent, and this still more or less persists today.
* desegregation. This is the big one; prior to the civil rights era, suburbs are expanding rapidly, but cities are still growing. The moment Brown vs Board of Ed passes in 1954 all hell breaks loose. The real estate practice of blockbusting gets into full gear, where real estate agents spook the white people out of a neighborhood by having one black family move in; they proceed to buy the houses on the cheap from white people fire selling as fast as possible, and then take advantage of black and minority sellers. Whites move into suburbs in droves, because it's "where the good schools are" without the minorities they used to be legally separated from. And this is a national phenomenon. Even today, we see whites flee school districts with increasing minority populations; they do so even in districts where the minority groups are affluent and educational metrics remain positive, like Cupertino, CA or Johns Creek, GA: https://psmag.com/news/ghosts-of-white-people-past-witnessin...
Exactly. I said “don’t like” to avoid making this explicitly about racism but it’s true. And those planners that made these cities people currently complain about had droves of people who “didn’t want to be near other Americans of another color or class” and loved car filled suburbs and strip mall towns.
* the aforementioned highway boom, but this is not enough to actually kickstart the whole thing; most European nations also had a highway boom around this time with much less sprawl
* lending standards. Prior to the Great Depression, banks are wholly in control of mortgage lending. The collapse of the economy also collapses the banking system and the housing market; banks have to foreclose on properties that are no longer worth anything. As part of the bank stabilization efforts, the FHA creates national standards for loans that it will insure. These standards are restricted to single family homes, and to properties without commercial (small businesses have a really high rate of failure). This has the effect of encouraging banks and developers to stampede into single family suburban development; the cost of financing is a lot cheaper because of the Uncle Sam guarantee, and it's a lot more profitable as a result. No other type of property is given this kind of preferential treatment to this extent, and this still more or less persists today.
* desegregation. This is the big one; prior to the civil rights era, suburbs are expanding rapidly, but cities are still growing. The moment Brown vs Board of Ed passes in 1954 all hell breaks loose. The real estate practice of blockbusting gets into full gear, where real estate agents spook the white people out of a neighborhood by having one black family move in; they proceed to buy the houses on the cheap from white people fire selling as fast as possible, and then take advantage of black and minority sellers. Whites move into suburbs in droves, because it's "where the good schools are" without the minorities they used to be legally separated from. And this is a national phenomenon. Even today, we see whites flee school districts with increasing minority populations; they do so even in districts where the minority groups are affluent and educational metrics remain positive, like Cupertino, CA or Johns Creek, GA: https://psmag.com/news/ghosts-of-white-people-past-witnessin...