One of the things Garber and MLS brass are always going on about is "footprint": the size of area that is 'covered' by an MLS team. For instance, DC United's 'footprint' covers not just the DC area, but Baltimore, Delaware, West Virginia, etc.

MLS wants to be a national league, which means being followed even in places that don't have a team. Assuming they are planning for only a 20 team league, I am sure one of the crucial issues they'll be looking at in expansion isn't just what cities look like they might support a team, but how "efficient" that city would be in spreading MLS' footprint.

By that standard, Portland would probably be an inefficient use of a franchise. Portland is small, and more important, Seattle's footprint will cover much of the Pacific Northwest already. In other words it doesn't really do all that much to spread MLS' footprint.

Montreal, on the other hand, would have a huge footprint. Quebec has 7m people, but more important, unlike Oregon where you'll probably have some people supporting Seattle, I am guessing that most Quebecers will only follow MLS if there's a team in the province.

But of course, if they are interested solely in maximizing audience size, that means expanding to as-yet-unrepresented areas: the south, or the southwest, both notorious for their awful fans. So it should be interesting to see how the league decides to balance sheer audience size/footprint against audience passion.

I wish I found my MA thesis this interesting.