I-5 rivalry

The I-5 rivalry was a National Basketball Association (NBA) rivalry between the Portland Trail Blazers and the Seattle SuperSonics. The two Pacific Northwest cities are 180 miles (290 km) apart and connected by Interstate 5. The rivalry ended in 2008 when the SuperSonics were relocated to Oklahoma City and became the Thunder.

On July 18, 2006, after unsuccessful efforts to persuade Washington state government officials to provide funding to update the SuperSonics' KeyArena, Howard Schultz and Basketball Club of Seattle LLP sold the SuperSonics and their sister team, the Women's National Basketball Association's Seattle Storm for $350 million to Professional Basketball Club LLC (PBC), an investment group that was headed by Oklahoma City businessman Clay Bennett. On April 18, 2008, NBA owners approved a potential SuperSonics' relocation to Oklahoma City in a 28–2 vote by the league's Board of Governors; only Mark Cuban of the Dallas Mavericks and Paul Allen of the Trail Blazers voted against the move. The approval meant the SuperSonics would be allowed to move to Oklahoma City's Ford Center for the 2008–09 season after reaching a settlement with the city of Seattle.

Seattle and Portland have had rivalries based on various sports teams. Of the five major sports leagues in North America, the two cities each currently have franchises in Major League Soccer with the Timbers and the Sounders, which have played annually sinces the Timbers joined MLS in 2011. Previously, the two cities had various incarnations of the current professional franchises in leagues such as the North American Soccer League and USL. The top women's soccer league in the U.S., the NWSL, features a rivalry between the Seattle Reign and Portland Thorns. Additionally, the Oregon–Washington football rivalry is one of the most played rivalries in NCAA Division I FBS history, and has been played regularly since 1900.

History
The first meeting between the Blazers and Sonics occurred on September 30, 1970, in a pre-season exhibition game held at the W. F. West High School gymnasium in Chehalis, Washington, midway between Portland and Seattle. The teams were immediately projected to be rivals, owing to the close proximity and existing rivalry between the Pacific Northwest cities. The Trail Blazers were a new expansion team for 1970, while the SuperSonics began play three seasons earlier in 1967.

Oden / Durant
Both teams beat long odds to emerge as the winners of the 2007 NBA draft lottery. Portland, with only a 5.3% chance, received the number one selection. Seattle, at a 9.7% chance, won the second pick. Their lottery luck and the presence of two generational prospects in the draft fueled instant hope for the revival of both franchises.

In the 2007 NBA draft, Portland selected Greg Oden as the draft's number one pick. Seattle followed, selecting Kevin Durant at number two.

Cruelly, neither city's fanbase would enjoy success from the draft. Oden was plagued with injuries and would play only 82 total games for the Blazers before being waived in 2012. Durant earned the 2007–2008 NBA Roookie of the Year award with the SuperSonics, but his addition was unable to prevent the team from being relocated to Oklahoma City the following year, where they began play as the Thunder.

Hiatus (2008–present)
The Blazers' rivalry did not continue with the newly relocated Oklahoma City Thunder, despite that organization's past history in Seattle and both teams continuing to play in the Western Conference Northwest Division.

Both cities gained Major League Soccer teams in the years since the Sonics left, with the Sounders beginning play in 2009 and the Timbers in 2011. The Portland Timbers–Seattle Sounders rivalry, which dates back to the 1970s, has continued the civic rivalry, as has the three-team Cascadia Cup with Vancouver Whitecaps FC (former home of the similarly relocated Vancouver Grizzlies NBA team).

The Blazers eliminated the Thunder from the first round of the 2019 NBA playoffs on a Game 5, 37 foot buzzer beater 3 by Damian Lillard. Lillard mockingly waved goodbye to the Thunder after the shot, and would later comment: "What can I say? That was for Seattle."

On October 3, 2022, the Blazers played in a "Rain City Showcase" preseason game versus the Los Angeles Clippers at the newly renovated Climate Pledge Arena in Seattle.

Postseason

 * 1978 Western Conference Semifinals: SuperSonics won, 4–2
 * 1980 Western Conference First Round: SuperSonics won, 2–1
 * 1983 Western Conference First Round: Trail Blazers won, 2–0
 * 1991 Western Conference First Round: Trail Blazers won, 3–2