I forget that actual reference.
But there was an article or map or something talking about the placement of towns, I think, back east (or the south, or Virginia).
Simply, the towns were placed within a days travel of each other. And the communities they served were, effectively, about a 1/3rd days travel in radius. That's how far folks would go to get into town, and being a day apart facilitated long range travel instead of camping in the wilderness.
The towns were basically small towns designed to serve those local communities. Cities formed on the intersections of such roads to support more trade and traffic.
I don't recall if it talked about towns along rivers where transit might be faster.
But it was an interesting article with a map of actual towns.