USHL and The OHA
The newly created Thunder Bay Twins started in the American United States Hockey League (USHL) in 1970, when the USHL was operating as a semi-professional senior ice hockey league.
At the end of their final, 1974-75, season in the USHL, the Twins challenged and won the Western Canadian Senior "A" Championship (Thunder Bay is in the western portion of Ontario) and earned a berth to play for the Allan Cup national senior championship—the first Thunder Bay entry since the 1955 loss by the Fort William Beavers. The Eastern Canadian finalist was the Barrie Flyers of the Ontario Hockey Association Senior A League (OHASr). The 1975 Allan Cup opened with the Flyers winning two of the three games played in Barrie, with the Twins winning three straight games when the series moved to Thunder Bay, giving the team their first Allan Cup Championship as the Twins, and the first to Thunder Bay since the 1939 Port Arthur Bearcats.
The Thunder Bay Twins moved to the OHASr for the 1975-76 season, brining the Allan Cup to the league it had just defeated to win the cup. The Twins played in the OHASr through the 1978-79 season. In those four seasons, the Twins won two regular season championships and one league playoff title.
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