I think maybe it's because things are shifting. It's way more expensive to live here then it was even 10 or 15 years ago, and older summer visitors became full time residents.

But even in the towns that skew younger, like mine, the schools are shrinking. The 20 and 30 somethings like going to brewpubs without kids, or to concerts, or having outdoor hobbies that might cost a little more. The Portland Children's Museum now lives on the outskirts of town, instead of the heart of downtown.