Uh well. Here in Texas you have a couple of brands of Americans:
You've got the hicks. Many of them live in the country, or were born there, but others live in the city but are somehow still hicks. These hicks generally do not understand anything relating to a foreign country. They also do not seem to understand why anything that is not American exists. When they speak of foreign countries (which most often is because they're talking about a war, like the Korean War), they speak of them as abstract things, things they have no real understanding of. Certainly places devoid of discernible or significant culture. I exaggerate, but only somewhat.
Then you have your dumbass suburban types. They go from place to place in their comfortable lives, not aware of less fortunate people etc. They are generally the kinds of Americans you hear about that can't find Iran on a blank map. They just don't care about anything outside their area. They are better informed, just because they spend a long time on the internet, and may even have political opinions, but in general these are secondary to them; they do not care about issues that affect us all. As such, when they meet an international person, they will probably unknowingly belittle them, asking about insulting things. Say the person is Vietnamese, they might ask if in Vietnam they shit in holes. Not in as many words obviously. And these are the more tactless of this ignorant suburban class.
In the more multicultural areas of the states, like where I'm from (Sugar Land, TX), this is less common, but there is still this general ignorance of the wider world, which is paradoxical given that 50% of the people are immigrants. It's like, to them, there is the US, the home country, and nothing else. They are little better.
Then there is everyone else. They are immigrants, your average joe who happens not to be a hick, worldly liberal types, or just intellectual types who happen to enjoy watching PBS or travel shows. These people are usually quite nice, and make up a large share of us Americans.
One can only hope that last class of people is how the world sees us. Alas, I think we are usually seen as hicks.
To Chris. You mentioned Toronto as a multicultural place, and I agree that it is (loved visiting). However I think when you said that Canada is more multicultural than the US, you may have been thinking of only some of the US. Many many places have large communities of non-black non-Latino non-white people. You have Desis everywhere, Asians everywhere, Persians, Palestinians, Hungarians, Africans, whatever. There are a lot of them, you just have to be in the right places.
(By that I mean San Francisco, Los Angeles, Phoenix, Portland, Seattle, Houston, Dallas, Austin, New Orleans, Miami, Atlanta, DC, NYC, Boston, Philly, St. Louis, Chicago, and some others)