As a Canadian student for a number of years in American schools, the only thing I ever discovered that really made Americans mad was to describe the anti-Catholic, intolerant, racist elements of the American Revolution and its immediate aftermath. When we had class presentations, I used to pick as my topic either the failed American attempts to persuade Quebec to join their Southern neighbours (treated as a hilarious marketing disaster) or the forced expulsion of the Loyalists, or the British freeing of black slaves who fought against the Americans and resettling them as free people in Nova Scotia and elsewhere. These never failed to get a rise out of everyone, and made me subject to any number of schoolyard fights. As far as I can tell, this still seems to be untouchable.

But mostly things are much better: they seem to have absorbed the horrible treatment of the Cherokee, etc., and have almost begun to think about the long sad history in Latin America. The great thing about America is that it has thousands of American people inside willing to point all these things out and scream about them. It is big and yappy, which is great. My country has about 15 pointing out what goes on here, which is why they are so tired all the time. Everybody else is out shopping.
yours, Peter T.