Asked what has most changed about Sounders-Timbers games since he played in them as a Seattle midfielder in the early 1980s, Sounders manager Brian Schmetzer concentrated mostly on the sheer size of the thing.
Mirroring the league as a whole, the crowds, television ratings and casual interest have all gotten bigger; Schmetzer noted with wonder that some family members in Germany can now tune in to some of his matches on Eurosport. With increased attention comes higher pressure, and you can feel that tension infused into the action.
"In terms of what we feel, during the three-hour drive back and forth, it does feel a little different," Schmetzer said. "Stakes are a little higher. The games are the same. They were physical back then and they're physical now."
More than anything else, however, the weight of history has increased in heft. Sunday night's showdown at Providence Park will be the 101st matchup between the two Cascadian clubs, dating back to the North American Soccer League and including showdowns in the minor leagues in the 1990s and 2000s. Each edition has added to the previous ones, like the accumulation of scar tissue.
"A lot of history has gone by," Schmetzer said. "All of the history between the two clubs adds to the pressure, the spice, all of the intangibles. Subtle changes, but basically the same."
That is what makes Sunday's culmination of Rivalry Week unique in MLS. Compared with Seattle-Portland, the roots of the other matchups have barely even scratched the surface.
That's not to say that they won't be entertaining in their own right, or that the emotions will be any less raw during New York City FC vs. New York Red Bulls, Orlando City vs. Atlanta United (Friday at 8 p.m. ET, ESPN/ESPN Deportes) or LA Galaxy vs. LAFC (Friday at 10:30 p.m. ET, ESPN/ESPN Deportes). All around the league, geographic and historic rivals will be facing off, and no matter how new, each of them comes imbued with preconceived storylines.
NYCFC and the Red Bulls have played each other only 13 times prior to Wednesday night, but there have already been results that will long live in memory: Red Bulls 7, NYCFC 0 first and foremost among them. This matchup already has the tendency to bring out one or the other's best, and its biggest stars -- Bradley Wright-Phillips and David Villa -- have more often than not risen to the occasion. (There have been uglier aspects to the Hudson River Derby, too, that underline the danger in stirring up and marketing tribalism and passion.)
Orlando-Atlanta brings together two clubs that have thrived in markets most northerners regarded skeptically before hugely successful inaugural seasons. This is even younger than the Battle of the New Yorks -- and has had moments that have felt more than a little bit contrived -- but this, too, feels like fertile ground in which to grow.
"I don't think that it compares to some of the bigger ones like Seattle-Portland, or even with the New York City teams, but you can sense that definitely the fans are into it," Atlanta defender Michael Parkhurst said. "... We're well aware of what's going on off the field. We understand that their fan base doesn't really care for us, and that makes it even sweeter when we go down there and get a result. We know it means more for the fans, and so it means more for us.
"Even if it's not a true rivalry yet, it might get there. This might just be the beginning."
Houston-Dallas, Toronto-Montreal, Colorado-Salt Lake -- the whole Rivalry Week slate will climax on Sunday night, with the most raucous and longstanding of them all.
"There's no disrespect on my part to all the other cups that the league has invented," said Sounders goalkeeper Stefan Frei, who once played in the so-called Trillium Cup for Toronto against Columbus. "But right now, I'm watching the [Amazon Prime] documentary about Manchester City, and when they go against Manchester United, that's a real thing. That's not something that's just made up. People care. It's in your blood, and in your DNA. The Trillium Cup, I'm sorry, but that's a very far-fetched Canada vs. USA that doesn't really do anything.
"There's something here. There's real animosity. When we're going down there this weekend, they're not gonna be nice to us. There are real emotions involved, and that's the way it should be. I don't know if this is the only one, I've only been in a couple [rivalries] in this league. But I remember being in Toronto, and getting ready to watch Portland versus Seattle. I think that says something."