The ignorance, and zenophobia, displayed in this topic is almost amusing.
First of all, the United States of American does not have an "Empire". Unlike the British, we have handed back all lands taken in battle that were not part of North America. And, even when we totally defeated Mexico, we made no effort at all to annex that country.
Second, the country is FAR from collapse.
Canada is a LOT closer to a breakup than the USA is. If Quebec ever breaks away, the rest of Canada will shatter in less than 50 years. Virtually every study done, has shown that this is the case. The Atlantic Provinces would be cut off from the rest of Canada, and that kind of situation almost always ends up in the cut off part either going independent, or joining another country.
Should Quebec leave, what would prevent the Prairie Provinces from also seceding? They really don't have all that much in common with Ontario, and they DEEPLY resent the lack of a voice in the Federal government. It is quite likely that if Quebec went independent, the Prairie Provinces would most likely petition to join the USA.
So, what is left? British Columbia is well over a thousand miles away from Ontario. How long do you think that kind of an arrangement would last?
Rather than thinking about "Merging" with the USA (and there is absolutely NO real interest in the USA for such a thing), you had better worry about what the future holds for Canada.