And parts of the US

[NewHope]

It is the insistence, as a first consideration, upon the interdependence of the various elements in, and parts of, the United States--a recognition of the old and permanently important manifestation of the American spirit of the pioneer.

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For convenience of analysis, I "recover" the writing above as:

As a first consideration, it is the insistence upon the interdependence of the various elements in the United States, and it is the insistence upon the interdependence of parts of the United States--a recognition of the old and permanently important manifestation of the American spirit of the pioneer.

I didn't understand " upon the interdependence of parts of the United States". Is it like " upon the interdependence of all states of the United States"?

[Tdol]

Yes- the states need each other.

[NewHope]

Thanks for confirming, Tdol. :)

[Tdol]

Originally they said 'These United States' rather than 'The United States', which gives an idea of the way they saw the nation.