[ElfinTrousers]

> I would guess that most people from outside the states are familiar with the geographical size of the country

If they do they don't act like it: my experience has been like the OP's, in that non-Americans tend to assume our society and culture is a lot more homogeneous than it is.

[jhonof]

Conversely, as an American, American's tend to assume their culture is a lot more heterogeneous than it really is. Tons of people don't travel outside the country because they think that the US has everything when it doesn't at all.

[ElfinTrousers]

To be fair, the US doesn't have everything, but it does have a lot, so I can see how you could get this idea if you weren't a particularly imaginative or curious person.