From my perspecive as a USian, I'd disagree. I remember Million Dollars was also a huge hit in the US and they toured a ton internationally, even before One Week. They played every major venue in the US (see Rock Spectacle, which was a live album that was also a hit in the US). I'd call them a pretty big act internationaly.

For Canada, I'd pick Bruce Cockburn (who wrote Lovers in a Dangerous Time), the Cowboy Junkies, Fred Eaglesmith, the Tragically Hip, or maybe Great Big Sea. Most of them have never had a proper international presence.