There is now the Katahdin Woods and Waters National Monument in Maine--although that was (and probably still is) controversial among some locals. It's fairly remote by northeastern standards. It's adjacent to Baxter State Park but the latter significantly limits cars in the popular area of the park.
The issue for locals wasn't so much crowding as I recall but concerns about restrictions to traditional sporting uses of the land. I haven't really followed how all that played out.
Relatively recent. Basically a big land donation from the Burt's Bees co-founder finally helped made it happen. And, yeah, although the National Parks tend to be "better" (i.e. more compelling), the distinction is mostly a political one. (I see they allow hunting in certain areas which also probably helped move it over the finish line.) At least in the vaguely recent past, most properties become National Monuments before they become parks. Acadia was Lafayette National Monument before it became a national park.
I haven't been up there yet. Soon. But like a lot of Maine lands in that general area, it's probably more paddling/fishing oriented than hiking (at least if you're into summits). (Even a lot of Baxter other than Katahdin is like that.)
The issue for locals wasn't so much crowding as I recall but concerns about restrictions to traditional sporting uses of the land. I haven't really followed how all that played out.