Visitors from the United States are famous all over Europe for confusingly proclaiming to be Polish, or German, or Irish, while appearing to actual Polish, German, and Irish people to be nothing more than clearly American. To explain why this happens, I'm going to explore an exception: those Americans who call themselves so.
This is a map of counties in the United States for which "American" or "African American" was the most common answer to the following question found on the long form for the 2000 census:
"What is this person's ancestry or ethnic origin?"
7.2% gave answers the Census Bureau interpreted as "American". The precise language I'm using is important because the actual form had an write-in answer space covering two lines. Those respondents who used this to report two non-"American" ancestries, such as "Italian" and "Puerto Rican" were counted as both. Others, who wrote something on the order of "German American", were counted solely as "German" on the basis of the Census Bureau's interpretation that those people intended a "hyphenated American" answer.1
It is evident from the first map and this one that "American" ancestry is reported primarily by white Southerners. At first glance it appears to be a very Southern phenomenon. 7.2% of the United States population in 2000 is about 20 million people, so for "American" to form the plurality in so many counties, it must be quite dominant where it is present. Indeed, 11.2 million out of the 20.2 million live in the South, 4.2 million in the Midwest, 2.6 million in the West, and only 2.2 million in the Northeast.2 Yet there are 13 states outside of the South where "American" makes it into the top four. Some of these can be explained through them being largely settled from the South. Missouri, for instance, was settled in fairly equal measure by Kentuckians and Tennesseans coming up rivers from the Mississippi Valley, Northerners from the Upper Midwest, and 19th century German immigrants, but just like immigrants to a city, settlers of certain origins concentrated in certain places.
Yet what we are really dealing with here is maps of memories, not of ancestries. Ethnic identity in the United States, just like clan or tribal identity elsewhere, comes from a kind of folk genealogy, the memories of our grandparents. Whether we are dealing with Alabama or Maine, what the counties in the first map have in common is that they have received relatively little immigration from outside the United States since 1760, having been settled primarily by internal migration from earlier populated centers where ethnic mixing had already occurred. Other than the grandfather whose parents immigrated to Missouri from Poland and the great-grandfather from Scotland, my own stock is this kind.
My grandparents' grandparents were already mutts of Manifest Destiny, their identity tied primarily to their own republic, not primarily because of any kind of personal ideology they held about Americanness, but because their particular mix (the British Isles, a bit of the whitest, north-westernmost parts of Continental Europe, and maybe some Indians and Africans they were ashamed to talk about) is precisely the ethnic identity that the young republic had assumed for itself. They were Americans in the way the newcomers from Silesia and Sweden were not, because telling what they were would be too long of a story.
Another story from the 2000 census is that the number of people reporting "American" went up 63% from the 1990 total, the largest single numerical increase for an ancestry choice. In demographics, an increase in population is either due to immigration or an increase of births over deaths. This is not the result of immigration. People from other parts of the continent overwhelmingly list their ethnicity as "Brazilian", "Salvadoran", etc., not "American". It is not the result of an increasing birthrate among those who identify themselves as "American". It is not the result of a patriotic upswell. Needless to say, the 2000 census predates September 11, 2001.
It is the result of deaths, though not directly. People's grandparents, their sources of identity, are increasingly from a time where their own grandparents were of mixed origin, from a time when Scots-Irish and Germans had started to become accepted into that Anglo-Saxon Americanness so pushed by the school textbooks, popular culture, and mass media of the white republic. Whenever people with a belief in Anglo-Saxon supremacy and American destiny felt threatened in any particular area to be pushed into a minority status, they tended to expand their group to include a few more ethnic groups. This process has continued unabated until now, influencing and being influenced by the way people intermarry. After the Scots-Irish and Germans, Catholic Southern and Eastern Europeans and Irish started to be accepted as "white", then Jews, and now, increasingly, the more affluent and/or lighter skinned Latinos and Asians.
This process is the subject of another post (or many others), but suffice it to say that it will influence the United States's conception of its own ancestry in the same order, and that it differs by region. Younger people are already in the generation where their grandparents were likely, in Midwestern cities, to be a mix of Catholic and Protestant, in the Northeast, to be Italian and Jewish, in Hawaii, to be Japanese, Filipino, and Portuguese. In other areas, like the Upper Great Plains, Scandinavian and German dominance is high enough and migration from other parts of the world low enough that particular ethnic answers, like the Finnish of Northern Michigan, will probably remain dominant for a while.
Some will, when asked, pick the one of their ancestries they like, that they are more comfortable with, or, for people who think about their father's side alone, the place their last name comes from, but many more will decline to answer or put something like "American". Expect the answer "American" to increase greatly again in 2010 and thereafter as a percentage of the population who identify themselves as white, particularly in those states where "German" and "American" currently co-exist at a high level.
1. United States Census Bureau. Summary File 3: Technical Documentation, B-5.
2. United States Census Bureau. Ancestry 2000: Census 2000 Brief, 6.