I'd like to recommend very strongly that if you can, watch the channel 4 series, just 3 episodes, fascinating.
"School Swap"
"UK big-city diversity collides with small town America, as teens from London switch lives, and schools, with high school students in rural Arkansas"
Its an all white quiet small town with just one black girl in the High School, with a big London comprehensive (clearly one thats doing pretty well, and very multicultural).
In terms of the "Special Relationship" I doubt any of the US kids had heard of it but they were very aware of the UK being the only English speaking country across the pond and that having significance.
It didn't deal with political issues at all - its quite light on the sunny side - there were a couple of uses of the N word from US students but not a lot made of it - but it was fascinating to see the cultural differences, some quite subtle.
But what also struck me is how very different it would have been to say swap with an inner city Chicago school or one of the other many "americas' there are - huge country, lots of differences.