The Diocese of Duluth, MN was formed in 1889 and consists of Aitkin, Carlton, Cass, Cook, Crow Wing, Itasca, Koochiching, Lake, Pine, and St. Louis Counties in Minnesota. The map provided plots the locations of the Polish Roman Catholic Churches in this diocese. Given addresses were usually of the rectory and not the church building itself. The map markers correspond to the church building if you zoom in close enough (they will put you at the front door). The Polish Catholic churches were identified based primarily on The Polish-American Parish published in 1963 by the Orchard Lake Schools, Henry P. Mucha, editor. It's not always authoritative. For example, St. Mary Church in Keewatin, MN is listed as Polish. Reading a history of the town does not support the claim. In the biography section of the Keewatin history, I only found one Polish family. As such, I have not included that church on the map. At the same time, St. Joseph Church in Gnesen north of Duluth is not listed at all. The town is named after Gniezno in Poland and history supports its claim as a Polish parish. Some of the other churches have apparently closed and now used by other denominations. If you click on the church markers on the map below, the information box will show the new name.