Yes, but it's heavily concentrated into a local area and with a long history and culture of its own completely separate from the Anglo-American.
I know that, I was saying that if we did annex all of Mexico for whatever reason then the population would be a quarter at the most but not half.
Anyway I think Mexico was more likely to be annexed by the US. Maybe it’s because I'm not being creative enough but I can't recall any moment in OTL that we came even remotely close to annexing Canada at least through force. I don't care if they speak English or not the entire British Empire had there back, the challenge a military expedition would only be rivaled in OTL by the Nazis trying to annex Russia, and even if our ragtag army managed to win Canada then so what? All we get is a huge ice cube that few people would want to settle in. Woo hoo. Sure maybe we could take Canada in a world war like event but seriously I don't see how that would be easier then Mexico.
Now we could have annexed Mexico if we wanted to the problem was we just literally didn't want to. And I'm not saying it's impossible to annex Canada I just think that Mexico would be easier then Canada.