Danish activity in America before the nineteenth century includes Danes in the Revolutionary War, and travelers to Pennsylvania, Wisconsin, and Lake Michigan. Immigrants between 1800 and 1840 included seamen, artisans, and adventurers, but immigration in large numbers began in 1840, when the Mormon Danes arrived. While Norwegian emigration began in 1825 as a flight from religious persecution and was followed by a mass migration of rural folk, Denmark's laws were comparatively benign toward dissident sects and once the movement began in the mid-nineteenth century it included both rural and urban emigrants. Indeed, religion was a relatively minor factor compared to the increase in the birth rate and the economic difficulties of a small country faced with a rapidly increasing population. Only Danish Mormons can be said to have emigrated for religious reasons, and theirs was not a flight from persecution so much as a gathering-in to "Zion" of co-religionists. Other Danish religious life in America was characterized by the pervasive influence of the Gruntvigian/Inner Mission schism, a phenomenon unique to the Danes, and by familiar religious symbols brought from Denmark. After 1850, non-Mormon emigrants were leaving Denmark primarily for economic reasons.

Works on genealogy listed here deal almost exclusively with Danes who have immigrated to North America. For researchers who have traced a family or a community as far back as Denmark, the Library possesses an enormous collection of works published in Denmark. These may be identified in the Library's catalogs through subject searches by family name or place name. The collection is particularly rich in Danish family histories.