Complex sentence: In 1937, Spokane became a charter member of the Class B Western International League, the predecessor of the Northwest League, which played at Ferris Field from 1937 through 1942 and 1946 until folding during the 1954 season on June 21.
Split into simpler sentences: In 1937, Spokane became a charter member of the Class B Western International League, the predecessor of the Northwest League. They played at Ferris Field from 1937 through 1942 and 1946 until folding during the 1954 season on June 21.