This map shows the population density of English, Welsh, Norwegian and Swedish immigrants in the United States in 1870. Also indicated are “British-Americans,” illustrating migration coming from Canada.
The full title of this map is: Maps Showing the Distribution within the Territory of the United States East of the 100th Meridian of Certain Foreign Elements of the Population, I – According to their Number to the Square Mile (Absolute), II – According to their Proportion to the Aggregate Population (Relative): British Americans — English and Welsh — Norwegian and Swedish.