The Class B level league franchises were based in the Northwest United States and British Columbia.
Teams in the league included the Aberdeen Black Cats, Portland Buckaroos, Seattle Giants, Spokane Indians, Tacoma Tigers, Vancouver Beavers, Victoria Islanders and Yakima Indians.
As the Northwest International League, it consisted of two Washington–based teams and two Canada-based teams: the Seattle Drydockers, Tacoma Tigers, Vancouver Beavers and Victoria Tyrees.
On June 8, 1919, the league disbanded, with the Beavers in first place.
Hall of Fame baseball pitcher Joe McGinnity played for the Vancouver Beavers in 1918.