A few random thoughts
So we're butterflying OTL WWII.
IMO the US would be a vastly different place. OTL Great Depression and WWII broke a lot of social molds and assumptions. Women and minorities were allowed to do traditionally white-male jobs, people got into uniform and shuffled around by the millions at an unprecedented scale of collectivism. Social mobility became not just a cultural expectation but the American reality.
IMO racism would be questioned a lot less and more automatically maintained, North and South. People would stay put, not near the regional mixing you saw thanks to WWII and the Depression. Traditional relationships and values would carry a lot more weight with good and bad results.
The post-war baby boom was where the pent-up urges for consumption of people who'd sacrificed for four-five years finally got the feeling it's OK to want your own home, not live with the folks, put up with rationing, etc.
Population growth wouldn't have spiked as much. IMO suburbanization would have been far less of an issue without all the modular construction techniques the Seabees and Army Corps of Engineers practiced across the South Pacific, North Africa, and throughout the US making instant bases appear.
Without hundreds of thousands of guys learning and doing things flat-out,
allowing millions of people to see what can be done if the collective will's there... I don't think Levittowns are as much of an issue until maybe the 1970's.
You had three drivers to suburbanization:
- As mentioned before, much better construction techniques that allowed cheap mass-production of homes and civic infrastructure brand-new vs retrofitting as you would in built-up cities
- Less zoning issues starting from scratch as many suburbs did with "business-friendly" zoning boards instead of scrapping with the city machine politicians content to divide the current pie, not expand it.
- By the 1960's white flight from desegregation and urban crime illustrated how much many wanted to vote with their feet rather than stick to their old neighborhoods and deal with urban hassles.
I'm arguing that without to WWII to spur technical and social innovation,
the US would be a much more conservative, complacent, less dynamic society poorer in many ways vs OTL.
We'd still believe in technology, pluck, and so forth, but nowhere the gee-whiz progressivism that ruled from say, 1933 to 1970's Era of Emergent Limits.
IDK how conservative the US Zeitgeist'd be, but the socially experimental attitudes after WWII wouldn't encounter near the tolerance of OTL.
Change would happen to correct social injustices but nowhere near the urgency folks felt after WWII after confronting Nazi Germany and Imperial Japan or having an ideological competitor like the Soviets forcing society to identify and confront its flaws. I.e. the South finally adopts the Civil Rights Acts in the 1990's or early oughts.

