Many men reported to Duluth during World War II to work in the iron industry for the creation of everything from tanks to bombs to ships. Many of these men were also semi-pro ballplayers back home and enough of them worked in Duluth to start a Minor League system of their own. Since most other leagues were suspended, Wade Stadium was one of the only places holding good competition in the country. The Twin Ports League was given a Minor League stamp of approval and Minor League Baseball's only "Class E" status. The 4 teams were called the Duluth Dukes, Herald, Marine Iron, and the Superior Bays. Unfortunately, the league wasn't very successful and after July, folded for good.