The Cascadia Cup is the name of the trophy created in 2004 by supporters of the Portland Timbers, Seattle Sounders, and Vancouver Whitecaps, which is awarded each season to the best soccer team in the Pacific Northwest. The cup is named for the Cascadia region. The Timbers, Sounders, and Whitecaps have roots dating to the days of the original North American Soccer League. It was first contested in 2004, and was claimed by the Whitecaps. In 2011 the competition continued with the now Major League Soccer (MLS) sides Portland Timbers, Seattle Sounders FC, and Vancouver Whitecaps FC.

Seattle Sounders FC is an American professional men's soccer club based in Seattle, Washington, United States. The Sounders compete in Major League Soccer (MLS) as a member of the Western Conference. The club was established on November 13, 2007, and began play in 2009 as an MLS expansion team. The Sounders are a phoenix club, replacing the second-division franchise that played in the American Professional Soccer League (APSL), A-League, and USL First Division (USL-1) from 1994 to 2008, and carrying the same name as the original Sounders franchise that competed in the North American Soccer League (NASL) from 1974 to 1983.