The effects of large-scale immigration during the nineteenth century are very clearly reflected . . . with twenty of the forty-eight states in the contiguous United States (that is, omitting Alaska and Hawaii) drawing their largest population from Germany. Italian Americans predominate in New York State, Irish Americans are the largest in Massachusetts and New Hampshire, while Britons are the majority origin only in Vermont, Connecticut, and, through their Mormon origins, Utah. However, in Arkansas, Tennessee, Kentucky, and West Virginia the largest number self-declared as “American,” a category that no doubt encompasses many with ultimately British roots. In four southwestern states with historical ties to the early Spanish territories—California, Arizona, New Mexico, and Texas—the greatest number declared Mexican origins. In seven southern states—Louisiana, Missouri, Alabama, Georgia, North and South Carolina, and Virginia—the largest proportion declared themselves as African Americans.
In no states were American Indians in the majority, but when the states were subdivided into counties, they did make up the largest proportion of the population in parts of Arizona and New Mexico, Oklahoma, South Dakota, and Montana. These higher-resolution plots also showed that the overall German dominance in the northern half of the United States was punctuated by counties with their greatest proportions drawn from other European countries. Norwegians dominate in parts of North Dakota and Minnesota, while Finns are in the majority in some regions of Michigan bordering Lake Superior. In a few counties within southern Michigan and Iowa, Dutch Americans are in the majority, while Americans of French origin predominate around their former colony in New Orleans. Perhaps unexpectedly, there is an Irish majority in two counties in southern Washington State and around Butte, Montana.
Apart from the numerical dominance of European Americans in large swaths of the United States, the other subtler feature of the map is that so many respondents in the 2000 census knew what their ancestral origin was, at least sufficiently to declare it as such on the census form. This reflects a key feature of European American ancestry, which is that almost everyone either knows what their European origins actually were or has a strong belief and attachment to them. In complete contrast to Native Americans, there is no general uncertainty surrounding the origins of European Americans and therefore no pressing need to recruit genetics to help sort these out.