While there had been several Swedish immigrant colonies earlier in American history, notably the short-lived colony at New Sweden in Delaware and an ongoing community in Philadelphia, Pennsylvania, the Janssonist emigrants triggered a larger wave of Swedish immigration in the latter half of the 19th century. Letters home from Janssonists to their friends and family, telling of the fertile agricultural land in the interior of North America, stimulated substantial migration for several decades and the formation of a distinct Swedish-American ethnic community of the American Midwest including areas around Galesburg, Illinois as well as in Minnesota to the northwest.