Since Canada is so close to the US, it's easy to forget that it's a different country. Even though we feel at home there, we still need to take care of things like getting travel health insurance, since the US health care system doesn't pay for treatment outside the US.
There isn't much about getting travel health insurance for Canada that is very different from getting it for anywhere else in the world. One difference might be that Canada has a high standard of living, so you can probably expect that medical and dental services will cost more there than in some Third World countries. This is another reason to look for the best travel health insurance plan, not the cheapest one.
In terms of money, a basic plan usually covers you and your family for about $50,000 CAD (about $43,000 USD). This is usually enough to pay for ambulance service, lab tests, doctor's fees, a short stay in the hospital, etc. But if you think this isn't enough, there are companies that will cover you for more than USD 1,000,000. And if you go skiing in Calgary or fishing in Ontario, don't let a broken limb (which could cost between $400 and $500 with therapy, crutches, etc.) ruin both your mood and your finances.
There are many Canadian companies that sell travel health insurance to Americans, and there are many American companies that do the same for Americans going to Canada, so the options are endless. Just go to their websites and spend some time with the online calculators that let you put in your age, the length of your trip, the province of your final destination, and your health condition. In no time, you'll have a lot of options to choose from.
