"that the existence of government is just one small part."
I dont think you can qualify government as "just one small part".
America would not be in the same place today without the decisions taken over time by its leaders. The same decisions would not be made under a different system of incentives for a leader like a monarchy/anarchy
It wouldn't be the same place, but it would still have enjoyed the highest natural-resource to population ration of any nation in history. Coal, Iron, Oil, Natural Gas, Gold, Wood, Water, Arible land, Uranium, Aluminium, Copper, all in great supply. The only comparable nations I can think of are Australia and Brazil, and their relative wealth is rather well explained by the overall wealth gradient nearing the equator:https://en.wikipedia.org/wiki/Geography_and_wealth
