500 years ago is a hugely artificial point to start your forest comparison. For a fair comparison, you need to go back far enough to reach the peak of pre-Columbian civilization in North America. That civilization was heavily agricultural and cut down plenty of trees to make farmland. Old World diseases subsequently wiped out nearly the entire population, and the subsequent reforestation sucked so much CO2 out of the atmosphere that it may have substantially contributed to the Little Ice Age.
For a proper comparison, you need to look at more like 600-1000 years ago. I don't know what the result of that comparison is, or how accurate it can be given how little is really known about pre-Columbian North America, but that's what you need to look at.
The standard picture of North America being virgin wilderness inhabited by scattered tribes until the arrival of the Europeans is dead wrong. That's how settlers found it, but only because roughly 90% of the population had been killed off by disease not long before.
For a proper comparison, you need to look at more like 600-1000 years ago. I don't know what the result of that comparison is, or how accurate it can be given how little is really known about pre-Columbian North America, but that's what you need to look at.
The standard picture of North America being virgin wilderness inhabited by scattered tribes until the arrival of the Europeans is dead wrong. That's how settlers found it, but only because roughly 90% of the population had been killed off by disease not long before.