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Seems like several hundred thousand or more immigrants crossed those rough terrains on any of a dozen trails to CA, OR, and various other now states in wheeled wagons just after the fur trapping period phased out. Then, they built this country.

There was already a country here, although much of it had fallen to ruin by the time people cut wagon trails. Estimates vary widely, but between 10 and 80% of the indigenous residents did not survive the smallpox epidemic which accompanied contact with Europeans. Such a decimation or worse even of modern populations would seriously affect economy, society, culture, and even our technology.

For those who used rivers for their highways, the wheel wasn't a necessity. (Note that we still move a tremendous amount of cargo by water, and that the oldest of heavily occupied areas, with few exceptions, were along waterways or where the headwaters of several drainage systems were in proximity to one another.

Sure, wheeled travel has facilitated the development of areas farther inland, but it only has been practical since the construction of roads and railroads.

Take away a couple of aspects of this 'civilization', and we'd be on foot/horseback and trading via boat as well.