[No Left Turn]

I would say that 90% of the real work in making America was done by 1865.

This was what you said. You later amended your comment to say: The foundation for superpower status was built long before the 20th Century began.

You also said: In fact, the predicate was laid when the United States was still a mono-ethnic/Old Immigration country, the myth of the melting pot notwithstanding.

I agree that the principles that got us where we are were in place before the 20th Century, but most of the work was done in the 20th Century, by assisimilated immigrants and their talents. That will continue well into the current century.

[rogerthedodger]

Well, I wish I shared your optimism.