UPDATE 2: A Sounders official has told me those 500 tickets are, indeed, for supporters groups. I'm under the impression there will be some discussion about just how the groups will distribute those tickets, but these aren't just for "family-friendly" or whatever nonsense other people have been saying.
UPDATE: Keith Hodo, president of ECS, had this to say about the ticket allocation: "It's a good start but shouldn't be the end goal. Eventually we should honor the FIFA guidelines of 5% of tickets being allocated to away support.
"This is going to be the premier rivalries in MLS and in order to grow the sport in America we need more away supporters at all games. We're committed to working with the front offices of the clubs to ensure that we support and foster this rivalry in the right way. Eventually these derbies will be the ones that American supporters circle on their calendar. We want to get to the point where supporters from across the nation and the globe will be able to descend on Seattle, Vancouver or Portland and see a truly world class football atmosphere."
Although news that visiting fans would be allocated 500 tickets for Cascadia Cup games was reported at the Alliance Meeting, today that became official as MLS approved the joint plan put forth by the Seattle Sounders, Portland Timbers and Vancouver Whitecaps. Those tickets will be distributed by the visiting teams through the various supporter groups (at least that's how the statement reads to me).
"The approved plan to allocate 500 tickets for visiting supporters will help grow a rivalry that is unique to this region," Sounders owner Joe Roth said in a team statement. "The three clubs, along with Major League Soccer, are committed to fostering local rivalries as well as providing visiting supporters an opportunity to support their clubs on the road."
Supporter groups from all three teams have been vocal in their opposition to limits and even released a joint statement a couple months ago saying so. So far, the reception to this news has been cool, with many supporters expressing their displeasure.
That said, this is an obvious step in the right direction. MLS teams have little experience dealing with large groups of visiting supporters and this should be an interesting trial run. If all goes well, there's reason to believe the away allocation could be expanded in later years.