Labatt Brewing Company is owned by AB InBev, which is actually not American but Belgian. Definitely not Canadian though.
The answer probably depends on where you are. There are tons of small Canadian breweries that ship to the US. Steam Whistle Brewing is a very large independent brewery that just makes a Pilsner. They're probably big enough to be fairly widely available. Buy it in cans though. They're idiots for packaging in green bottles.