The Twin Ports League was an American minor baseball league that existed for six weeks (May 30 through July 13) during the wartime 1943 season. Comprising four teams based in Duluth, Minnesota, and Superior, Wisconsin, the TPL was the only league to be designated "Class E"—one level below the previously lowest minor league level, Class D—by the National Association of Professional Baseball Leagues.
According to Baseball America's Encyclopedia of Minor League Baseball, many of the players in the Twin Ports League were employed in the Twin Ports' war factories, dockyards and shipyards. The teams included the Duluth Dukes, Duluth Heralds, Duluth Marine Iron, and the Superior Bays. The Superior club was in first place when the league disbanded on July 13, 1943.
Only one player in the Twin Ports League eventually reached Major League Baseball—Ernie Rudolph, who pitched in seven games for the 1945 Brooklyn Dodgers.
Former major league player Wally Gilbert managed the Marine Iron team.