Compared to ecologically and topographically similar regions of Europe or east Asia, the northeastern United States is unusually heavily forested. One might think "well, yeah, the U.S. hasn't been settled by agriculturalists for as long and is less densely populated, obviously there's going to be less percent land cleared for farms," but this is not so! Everywhere in the northeast, our forests rise from what were once old fields. In 1860, for instance, Maine was only 60% forested by land area. Today, that proportion is closer to 90%.

We owe our current landscape to two great waves (and several smaller ones) of farm abandonment. The first happened in the decades after the Civil War, when for various reasons* northeasterners (mostly from New England) packed up their pitchforks and decamped to the midwest. This had been going on before the war too, of course, but up until then it had not been in numbers enough that the northeastern farms stopped being worked. There was always a son or two left to till up more stones from the Vermont field. But that changed after the war, and the fields started to revert to oak and maple and pine. Indeed, much of the early formal scientific study of American forestry and ecology happened in these old Yankee fields and young Yankee forests, by outdoorsy young men from Harvard with names like a Lovecraft protagonist.

The second great wave was in the Great Depression and World War 2, when for various reasons** people from all the rougher sorts of terrain the east has to offer - from West Virginia to Indiana's Brown County to the Ozarks and back to the Catskills - left their farms to come down and seek work in the then-thriving industrial cities. Much of the hilly landscape of the east that had previously been dotted with small subsistence farms, full of exactly the barefoot gap-toothed hillbillies who captured the imagination of urban popular culture with their exotic poverty and folkways when they suddenly appeared in Cleveland, or wherever, in 1933.

These pulses of farm abandonment have left very specific patterns written in the ecologies of the northeast. For instance, the fact that the poor ridgetop farms that were once extremely common in Southern Ohio and Indiana were nearly all abandoned in the 1930s and '40s means that the forests that now grow there are uniformly approaching their first century (excepting, of course, where there's been logging in the meantime.) This is almost exactly long enough for the process of ecological succession to complete itself, and the forests to move into their mature phase.

And so you read books written in the '50s, '60s, or '70s about these areas, and you notice how common early successional species are, everywhere chokecherry and black birch. Whereas today the only evidence you may see of the forest's relative youthfulness is a few very large bigtooth aspens nearing the end of their lives, surrounded by tulip poplars and chestnut oaks that will endure for many years after all the aspens are dead.

*Young men returning from war with a restlessness and a desire to leave home again; those same young men posted far from home during the war and realizing just how awful the New England soil is, lmao; Republican government policy writtrn explicitly to favor small homesteaders heading west; the late 19thc. crash in agricultural prices (as, in a few short decades, the Great Plains, the Australian wheat belt, parts of the Kazakh and Siberian steppes, the plains of South Africa, and the Argentine pampas were all put under the plow for the first time, and during an era of global free trade) making many small farms entirely unsustainable.

**Years of erosion on fields carelessly laid out on steep terrain; the Great Depression making running a small farm, ah, difficult; economic modernisation making staying as a subsistence farmer a damn foolish thing to do; new roads and automobiles making fleeing to the city easier than ever; and the TVA and other federal land grabs displacing hundreds of thousands of people.