While our culture is certainly more diverse than Norway's, I absolutely think that there are American values that, while certainly not held by all, do define us as a nation. Among them I would include:

- Pluralism

- A belief in the value of hard work

- A strong commitment to individual rights / individualism

- A certain degree of puritanism

- A belief in American Exceptionalism

- A belief that fairness should always be aspired to

- A fairly strong commitment to market capitalism

- A healthy dose of skepticism that government intervention is the solution to many problems

- A commitment that the "American Dream" is something that we should always strive to make real for everyone

None of those are American values or uniquely American. The belief in the value of hard work is a Puritan value, for instance. And everything else you listed is, to a certain extent (sometimes exceedingly so), shared by many other cultures. You think only Americans are skeptical of government intervention? You should travel to Turkey sometime and talk to some of my countrymen about what they think of the Turkish government. :)

Individual items in this list are certainly not unique, but I think that the list as a whole (with probably an addition or three) combined in the particular way that America does it is unique.

Yeah, but if you're willing to admit that these values are not universally or uniquely held by Americans, what is the problem?

If the Average American only holds 6 out of 10 of your imaginary Core American Values, what does it matter if we invite in a hundred million New Americans who also only hold 6 out of the 10, because they were from a different culture? Where is the assimilation problem?

(Also, "free market capitalism" and "skeptical of government intervention"? Really? Are you living in a bubble or just willfully pretending that the last 100 years of American history don't exist?)