In 2002 a bunch of Toronto fans came all the way to NC for the NHL playoffs since it was easier to get tickets here than in Toronto. Of course they lost that series . 
It’s not as obvious now, what with national cable broadcasts and every game available on the web, but it used to be a whole lot different. If you wanted to watch a pro sport you had to watch the local team; networks basically use to broadcast just one national game of the week and, aside from TBS and WGN, cable had nothing. I grew up in Ohio just a few miles south of the Michigan state line, and I didn’t know any Cavs fans because you couldn’t see their games. We got Detroit TV and radio but not anything from Cleveland, so nearly everyone was a fan of the Tigers/Pistons/Red Wings.
Considering that it’s a good hour from my childhood home to Windsor yet we could always pick up its CBC station (and it has always been carried on our cable because this is a big hockey town), I would figure that Detroit TV penetrates pretty far into the Windsor-Sarnia-London area and most there are Detroit sports fans. Last fall Rick Mercer riffed on Toronto sports fans being unfamiliar with the word “playoffs” (“What are playoffs? Do we need tickets? Do they play the games at the same stadium?”), so maybe team quality plays a role too.
I grew up in Sarnia, and hell yes there lots of Tiger and Red Wing fans in the area.
Strangely, here in Eastern Ontario (Ottawa valley area) there are a ton of Bruins fans. I really don’t know why, although I suspect Bobby Orr and Phil Esposito were responsible for attracting fans back in the 70s, especially Bobby.