[6] The strong cultural and trade links between the two cities in the new soccer rivalry, including the experience of Alan Hinton, who was a player-coach for the Whitecaps in two different stints before becoming a Seattle resident in 1979 and Sounders broadcaster.

[7] Hinton recalled the NASL crowds and significant presence of rival fans at away games: "It's a great rivalry...Years ago they'd come down in their thousands.

In the final season of competition between the clubs, the Whitecaps defeated Seattle 2 to 1 before 60,342 fans in Empire Stadium, the largest crowd to watch a match between the two in series history.

[9] The A-League ultimately became the USL First Division, which the clubs competed in until the Sounders made the jump to the first-division Major League Soccer in 2009.

The first match featured an early lead for the Whitecaps but the Sounders scored two goals from Mauro Rosales and Osvaldo Alonso after the 81st minute.

The first leg of the conference semifinals was particularly contentious, as teams nearly brawled while security guards ejected leaders of the Emerald City Supporters group for brandishing antifascist signs.

[5] After the scoreless draw at BC Place,[12] the Sounders took the second leg 2–0 from second-half goals from Clint Dempsey to send the club to a second straight Western Conference Championship game.

Montero went on to win the team's Golden Boot award in his first season in Vancouver, highlighted by a brace in his first meeting against his former mates, and then scoring a shorthanded equalizer in the midseason rematch.

[14] Between 2004 and 2008, the USL Seattle Sounders, Vancouver Whitecaps, and Portland Timbers competed for the supporter created Cascadia Cup, to be awarded to the club who finished with the best record in each season series between the three teams.