There are a couple of other reasons as well, the Obama Economy has had this effect as well as fewer people conceiving children, lost birth rate since the depression.
Also, the United States is getting older and fewer people of childbearing ages are in these states.
I think that trend might be close to reversing itself, however. During the Depression, families helped out at home, children helped in businesses, etc. etc.
I know I grew up on a farm and there wasn’t that much that we really got from the grocery store except fresh fruit and of course, baking and canning supllies.
We had
beef
lamb
pork
chicken
vegetable garden
some berries
lots of sweet corn since my dad was a seed corn dealer
our own milk because we ran a small dairy.
Fairly self-sufficient. I’m the oldest of seven (six living) children and we all helped out in our own way.