Dr. Nye lays out his case for the American progress afforded by certain technologies of the time. He asserts that the American narrative was created, in part, through stories of Americans' interaction with and progress by technologies. This narrative is also one concerned with progress. Progress is, arguably, integral to the American narrative.
Nye also asserts that the American view is one of dominance over nature; that Americans saw and continue to see nature as a place for use, and perhaps rather than a thing to be in awe of. This view, in large part, is a colonial one. The colonial history of the U.S. is an undeniable history, but, as Nye Asserts, this "history" and the narratives formed from it are often intertwined or even mistaken for one another.
I find this aspect of his argument especially interesting and true. Not everyone is a history major or a history buff. And, as William Faulkner demonstrates in Absalom, Absalom, History is extremely difficult if not exceedingly lost. Therefore, we have narrative. Though history and narrative are both "stories," it seems they depart from each other at different and even crucial points. This is not to say that technology in America has not been used to an extreme extent or that it is not part of U.S. history, but that it is the narratives of American use and interaction with these technologies that has become a large part of the cultural narrative.
From this narrative spawns many more ideas and even political views as we know them today. The idea that "progress" is improvement is definitely one of them. Not to get all environmental here, but the proliferation of industrialization in the U.S. and around the world could be seen as something quite contrary to this idea, insofar as nature/environment are concerned.