First, Ken's right. While US carriers under most plans will roam in Canada and vice versa, the rates are not always good, so you'll probably want a different SIM for each country.
Second, you need to know that not all North American carriers use SIMs (except for 4G LTE data). I don't know about Canada, but Verizon and Sprint don't use GSM technology, they use CDMA, which doesn't use a SIM. So, forget about them for your needs.
Third, the best source of information I have found for questions like yours is Prepaid GSM. Here's their Americas forum page: http://www.prepaidgsm.net/forum/forumdisplay.php?f=23
On the top of that page under "National Operators," you can get lists of the US and Canadian providers and MVNO's, then click on the links to see their various plans (which, of course, change all the time).
One option to consider, which contradicts some of what I said above, is T-Mobile's Simple Choice Plan. While in the US, you get a certain allotment of 4G LTE data (paying more gets you more); once the allotment is used up, your data slows down to 2G speeds, but doesn't stop. You also get unlimited calls and texts. However, when roaming in Canada under this plan, you get unlimited texts and 3G data, and calls are 0.20 USD per minute (sending or receiving). The cheapest eligible plan (one GB of 4G LTE data) is $50 per month plus various taxes, so it comes to about $65. It would be a one-SIM solution, and may be good particularly if your trip is long, or if you're going back and forth between the US and Canada a lot (so it doesn't pay you to get a "cheaper" plan for each country with higher start up or roaming fees). Note that for $10 or $15 extra per month, you can add unlimited calls to foreign countries; check their website for details. http://www.t-mobile.com/cell-phone-plans/individual.html
Note that the link I gave is for individual plans; if there are two or more of you traveling together, the rates get much better for "family" plans. Also note that T-Mobile's prepaid plans can be great for the US, and you can add the option for cheap international calls, but they won't roam cheaply in Canada. So if you can't get a postpaid plan (which Simple Choice is), you would then have to get a different SIM for Canada.