I actually discussed this a bit yesterday as part of a much larger reply to a question about the differences between Pre-Columbian Mesoamerica and the Eastern Woodlands. I'll quote the relevant section of that reply here:

While rivers, lakes, and the portages between them were absolutely essential to trade and travel in the Eastern Woodlands, they weren’t the only option available. The whole region was crisscrossed by thousands of miles pathways. Modern Mobile, Alabama served as the southern terminus for two major paths. One went north to modern Sandusky, Ohio; the other, which overlapped with the previously mentioned path for a while before branching off, went along the Appalachians, into Pennsylvania, New York, and onto Maritime Canada. To help illustrate the issue, here is a map of the major pathways of the Southeast.

While not as intensively constructed as Inca roads, they also weren't blindly cut into the forest. Paul Wallace, who studied the historic paths of Pennsylvania in the early* mid-20th Century, noted that the pathways were carefully chosen to provide direct, level travel while avoiding springs which would damage and wash out the path over time. There were, of course, necessary exceptions to this general rule. East-west paths had to sometimes sacrifice either levelness or directness to get over or around the mountains. These paths were so well placed, that before the development of cars, Euro-Americans continued to make use of them, widening them as needed to accommodate their increasingly wider vehicles, deviating from them only to avoid new obstacles like farms or to pass through new towns. According to Wallace, these deviations often proved detrimental, as the Euro-Americans were less cautious avoiding damaging springs. All in all, he compares the engineering of these pathways favorably to the transportation network in contemporary parts of Europe where carts and wagons were rarely employed (specifically making a comparison to 16th Century Scotland). For the volume of foot traffic these pathways saw, they were well suited.

*Just noticed that I had accidentally lumped Wallace in with William Myer and Frank Wilcox, who wrote their works on the pathways of the Southeast and Ohio, respectively, in the mid-20s and early-30s. Wallace did his work in the 50s.

I've driven the Natchez Trace Parkway several times, it follows the route of the old trail system and has several interesting sites along it. You can even see parts of the actual trail itself that have been maintained. Here is a small picture of a preserved section.