A year or two ago, realisticidealist invented this neat tool that tracks people's surnames and first names and shows in which US counties those names are over- or underrepresented relative to the national average. One constant trend I discovered is that Scandinavian surnames (Jacobsen, Erikson, Jacksen, etc.) were concentrated not only in and around Minneapolis, as expected, but also in Utah as well as heavily-LDS western Idaho.
What might specifically explain early Mormonism's appeal to Scandinavians, and presumably drove these populations to this region among the rest of Young's adherents?
It doesn’t, most Scandinavian American Mormons are of Danish descendent and converted in the 19th century in Denmark after freedom of religion was established, which accidental fell together with Mormons sending a lot of missionaries to Europe. The converts mostly emigrated to Mormon areas in USA. So the overrepresentation of Danish ancestry among Mormons is a artifact of this large early conversion, while the membership was relative small and other Scandinavians and later Danes didn’t have the same interest in Mormonism.
Danish ancestry USA