Question for the guys that download the maps and use them in the states: Does your device still tell you where you are w/o using any data (the true test would be if your data services are set to 'off')? '
So there's lots of ways to get the job done, just have to be creative or spend the cash.
1. Don't get a plan - use data - pay out the nose for it. You will probably not use more than 500mb for maps alone, as long as you remember to turn
everything else that fetches info off. That one email that you receive with a picture will cost you.
2. Get plan from your current Canadian provider - better than option 1 but still expensive depending on how much data you use.
2.5. Get a SIM card from a US carrier
3. Get a dedicated GPS app that has all the maps loaded already. All costs are up front and you will have this for many trips. This is part of my preferred way to go and is cheaper than a dedicated GPS device, which is another option for you.
4. Another little trick you can do if you don't want to pay any $, is to use google maps on your phone. While at the hotel that has wifi, just map your route for that day (select avoid highways cause you're riding the bike), then once you're at the zoom level you want to be in, trace your route so it loads the maps (then trace it back to the start - I find that if I tap on the locate me icon, it usually screws something up. However once back to the start point, I tap the locate me icon so it keeps me in the centre). Don't bother tapping START since you don't want it to give you turn by turn direction (you don't have access to data anyway). Then just go, your phone will have the maps already loaded and you can see where you're supposed to be turning. Not ETA or anything like that but hey, you're going to stop at Starbucks for a break anyway, you can do the same thing. If for some reason you don't have a section loaded, you can still see your way, just follow the blue line.
I did this on our trip a couple of weeks ago because my GPS app was routing me a 9+ hrs route and google was only 8 hrs. It worked well. If you are travelling in cities, wifi is everywhere so it's not a huge deal. If you plan on being in the country, wifi is harder to come by. If you are planning on travelling often then a more permanent solution would be better such as a hotspot device like MacDoc suggested.