The definitions in the Wikipedia article also state other figures. For one thing, in another part of it, they state that "Barely one-third (34 percent) of the w

The definitions in the Wikipedia article also state other figures. For one thing, in another part of it, they state that "Barely one-third (34 percent) of the world's forests are primary forests." After centuries of industrialization and explosive population growth in the human species, that percentage is surprisingly decent. Secondly for your U.S. figure, bear in mind that their baseline for the age of the cleared forests is almost 400 years. Even among trees, many don't live that long. You could easily have a truly ancient forest by any measure, that hasn't seen invasive human presence in centuries, filled with extremely old trees, but consider it what, secondary forest just because it's from the early 1700's instead of the 1600s?