The majority of people lived in villages until 1920 in the US.
US birth rates started dropping off not a generation later.
US birth rates started dropping off not a generation later.
That factoid doesn't mean much on its own.
Blaming the depression and word war is a bit of a stretch.
The transition away from communities where kids had autonomy, regualr access to adult-free spaces and also easy access to a wide variety of adults - the loss of all that massively increased parenting time and resources, from a few hours per week to 24/7 adulting.
Modern young parents now how to replace many diverse and experienced adults and impossibly simulate the autonomous and independent spaces where kids learned interpersonal and problem solving skills.
The closer we got to this, the less people wanted to have kids.