Something that has happened in recent decades is the development of a lot of places which are too dense but not dense enough, that is they become dense enough to have a lot of the downsides (such as extreme traffic congestion) of density, without being developed in such a way that the benefits of density (such as walkability) can be realized. Some places are more positioned than others to transition to a better state, with some tweaking of development codes, but some are likely to be stuck.
A few weeks ago I was driving around in burbs I remembered from when I was a teenager, only they weren't the same. This was... not an older suburb, but not a newer one either, probably a place which had its initial development boom in 60s-70s. The traffic was... incredible. Back when I was younger it was the archetypal quiet leafy suburb, but increased development in the area plus the fact that the area was increasingly a conduit to major highways without really having the roads to support such a role had really changed the place.
