It's tempting to think of the Vancouver Whitecaps-Portland Timbers as the Cascadia Cup undercard. The Seattle Sounders clearly have the largest following, the two teams are geographically separated by basically twice as much distance as either of the other two matchups and the raw hatred of Seattle-Portland isn't there.
But as this video reminds us, this is just as much a part of the rivalry.
It's also worth remembering that this rivalry had a couple years to grow, while the Sounders got a head start on their MLS journey. During the 2009 and 2010 seasons, they played each other seven times during the regular season and met in two-legged playoff series each year. Dating back to the NASL days, this will be the 72nd time they've met.
The point being that these two fanbases are very familiar with one another. Last year, the Timbers got the best of their matchup, but the Whitecaps are surely looking to gain a measure of revenge while also bolstering their playoff chances.