I guess my response will get to you a bit too late for this year, but just in case.
We traveled from November to April to the US, and I purchased a SIM card (right here in Canada) from Roam Mobility, and pre-activated for the date I was leaving. The plan costs +/- $35 (US$) per month and gives you unlimited free calling in the US and Canada, plus 5G of data.
Coverage was excellent, except in some state parks, and call quality was very good. I highly recommend it.
Note: as soon as you cross over back to Canada, it stops from working.
Additional note: I made the mistake of only purchasing a 3-month package, and I ran out in February. But adding additional time was a cinch once I was able to connect to free wifi in a museum.