The two earliest Kashubian American settlements in the United States were 1) in the Winona, Minnesota area (including the towns of Fountain City, Pine Creek, Dodge, and Trempealeau across the Mississippi River in Wisconsin, and 2) in Portage County, Wisconsin (including the towns of Polonia, Sharon, and Hull). The Winona settlement is traditionally dated to 1855, but hard data is lacking; the Portage County settlement can definitely be traced back to 1858. Winona is dubbed "Kashubian Capital of America", because of the largest population of Kashubians there.
After the American Civil War and the German Kulturkampf of the early 1870s, Kashubians emigrated to the United States in much larger numbers. While some headed for the Winona area and for Portage County, many Kashubians wound up living in major urban centers such as Buffalo, Detroit, Chicago, and Milwaukee. A smaller number of Kashubians settled in small farming communities scattered throughout Minnesota, North Dakota, and Montana. By the turn of the century, Kashubian Americans tended to identify themselves completely as Polish Americans, although in Winona (at least) the Kashubian language would survive for another generation or two.
1 Poles came to the United States legally as Austrians, Germans, Prussians or Russians throughout the 19th century, because from 1772-1795 till 1918, all Polish lands had been partitioned between imperial Austria, Prussia (a protoplast of Germany) and Russia until Poland regained its sovereignty in the wake of World War I.