When you read books and so forth written during the 18th and 19th century you get a real feel for what things were like back then. (Mark Twain is amazing at this..Huck Finn gets all the glory, but Tom Sawyer is a much better book in my opinion.) But it was fairly common for people of those times to go barefoot as soon as the weather allowed, and as someone pointed out earlier, if you do this on a regular basis, what "the weather allows" is lot earlier than for the rest of us. But spring and summer (and well into the fall, at least down South) People did not wear shoes except on Sunday to go to church. "Sunday go to meeting clothes" (which included shoes) were special and as the name suggests, worn only on Sunday and for a relativly brief time at that.
Don't forget the story of Daniel Boone sitting outside, relaxing in his Sunday clothes, shoes off (my emphasis, I assume if your feet have a steady diet of moccasins, "regular" shoes might be very uncomfortable) when Boone recieved word that his daughter Jemina and two other girls had been kidnapped by Indians. He immedieately took off after them. Took them three days to get them back, but they did.
(Right hand to God, there really is a point in here somewhere. I just sort of lost it..)
My guess is that moccasins were far more common along the frontier, folks in the villages and towns, (America did not have much in the way of cities back then) wore shoe, but some one back in the wilds of Western Carolina, or further, or in the "Kaintuck' or Ohio region wore mocs.