Split-season 1st-half winner: Duluth-Superior White Sox
Split-season 2nd-half winner: Winnipeg Goldeyes
Championship series: best of five
Visiting teams listed first, home teams second. Winning teams in bold.
9/3/1957
Winnipeg at Duluth-Superior, postponed, wet grounds
9/4/1957
Duluth-Superior 1, Winnipeg 9
9/5/1957
Duluth-Superior 0, Winnipeg 10
9/6/1957
Winnipeg 5, Duluth-Superior 2, 10 innings