I really enjoyed this essay, particularly as I had just finished The Crisis by Winston Churchill (not that one). The idea of the impact of living in a partially "civilized" environment (I use the term advisedly, as I'm aware of its implications re civilization vs. "savagery" and the normative implications inherent therein--nonetheless, it's the terminology of the author and the dominant paradigm through which most Americans, I think, see the history of westward expansion in US history.) on the broader development of "Americanness" is, I'm sure, not a new one. After all, the essay was written over 100 years ago.
But it did have several insights that struck me as novel and important, namely the advance of different levels of development at different rates--hunters, traders, adventurers, ranchers, farmers, etc., and the various levels of social order that each necessitated and developed. I would have liked to see the author put more flesh on many of the ideas alluded to in this short piece, including the backward influence of the frontier institutions on the more established parts of the country and especially on Europe.
I also would like to read more about the relationship between territorial expansion of the United States and religious missionary activity. Could this be a reason for the relatively more expansionist/millennarian tendencies in American, as opposed to Old World, Christianity? Just a conjecture.
At any rate, a paper that gets you thinking about all kinds of interesting connections, this feels like it could have been published in a sociology journal within the past ten years. Says the guy who definitely does not read sociology journals. But it does sound remarkably contemporary to my ear. I enjoyed it a great deal.