> The NE also went from 30% forest to 70% open/farming land to 70% forest 30% open in about 100 years as agriculturalism gave way to industrialization.
Source? It would surprise me to see that many people voluntarily give up their farmland rather than, say, selling it to industrial farmers or real estate developers.
If you are driving thru New England and pull over to any forest you can start walking and eventually you will find a short stone wall. These stone walls used to mark the borders of farm land but now they are in the middle of the forest. They are everywhere! Really gives you an idea of how much farming used to go on there.
In my area, once you get passed a point south of me, those walls are fewer and fewer. There are areas where it was never farmed and old growth trees still exist.
What is great is you can walk out to places and stand there and be reasonably certain that you're the first human to have ever stood in that spot.
I'm way up outside Rangeley, Maine. I even have true old growth and there weren't many natives in the area. So, there are some places where it's a good guess. They aren't easy to get to, of course.
It's because it was never really good farm land to begin with. With the advent of the Erie canal, railroads, and industrial farming techniques the competition from the really excellent farm lands of the Midwest made farming NE rocky terrain impractical.
I grew up in Vermont and the woods are full of old stone walls put up by farmers and cellar holes where their buildings used to be. Not just on the edge of the woods, but deep within them too. I'm not a student of farming but I don't think that New England is a particularly good place to do it. Lots of hills and mountains and rocky soil. As for real estate developers, there's a lot more money to be made in heavily populated areas of the country. Taking VT as an example, the state contains fewer residents than the Boise, ID metropolitan area does, and the largest city has fewer than 45K people.
edit: removed link to an article that has been posted several times.
Real estate developers pale in comparison to the sheer amount of land in the US. Hell, even just on the "wrong side of the tracks" in many very expensive cities there's often completely abandoned/disused land that's worth a tiny fraction of the land a half mile a way.
Once you get somewhere more rural/remote, the land is going to have even less value.
The landscape was largely unsuitable for large scale farming (tiny fields with thin soils among rough terrain), and most farming areas aren't near cities.
Lot's of people gave up on farming hardscrabble New England in the early part of the 20th century which resulted in reforestation. Farming is making a comeback in niche products, but nothing at the previous scales. This article (sorry for the paywall) gives a good summary: http://www.bostonglobe.com/ideas/2014/11/21/how-new-england-....
Just find some photos of places in the countryside of Maine, New Hampshire, Vermont, or Massachusetts from 1900 and compare to the same places today.
Or go walking through the forest, and count how many stone walls you have to clamber over. Every one used to mark the edges of a field or a pasture that was hacked out of the forest, and then was allowed to grow back up when farming the cold, rocky soil of New England was no longer cost-effective.
You're right - farmers generally didn't just let the fields lie fallow and become forested. Piece by piece, farmers sold their most marginal lands to housing developers, commercial ventures, etc.
Source? It would surprise me to see that many people voluntarily give up their farmland rather than, say, selling it to industrial farmers or real estate developers.