I agree with everything except 13; superficially American and Canadian culture are similar but they are not. I moved from the US to Canada because of that difference.
I do agree that we share a common North American culture. Travel in South America, and you will be called a North American.
In my travels, it is usually easy to tell whether someone is from Canada or the US. I've travelled within every province and territory in Canada except Nunavut, 33 states in the US, numerous Caribbean islands, and even so I feel that I have only skimmed the surface. Live and travel around North America, and you will discover a lot of diversity within this huge continent. Like the Gary Arndt, I encourage travel because of what you will learn.
Oh, there's definitely cultural differences - I moved from Canada to the United States for grad school, but I've stayed because I prefer it down here.
However, the deeper differences between the two countries aren't going to be immediately apparent when interacting with tourists. It's not hard to see how someone on another continent could equate the two countries.
