Largest Ancestry by U.S. County

According to the 2010 U.S. Census, America’s most populous ancestry groups were Germans (16.4%), African American (12.2%), and Irish (11.8%).

The most massive wave of Germans came to the United States through the middle of the nineteenth century, avoiding civilian crises and high unemployment rate. Nowadays, most German-Americans live in the non-coastal states, with the largest number in Maricopa County (Arizona).

Most African Americans are the descendants of slaves from Sub-Saharan Africa.

The great starvation of the 1840s triggered a mass emigration from Ireland. Within the 1820s and the 1920s, approximately 4.6 million Irish migrated to the U.S., many of them resided in big cities like New York City, Boston, Chicago, San Francisco, and Philadelphia.

The map below highlighted the national origin claimed by American citizens in each U.S. county.

Largest ancestry by country in every county
Map of Largest Ancestry by U.S. County
Reddit user: Bob_0101

African Americans and all the Natives presented on the map are not referred to as a particular nation, but they are still part of the wide range of different ethnicities present in the U.S. “Local Native” – people who identify themselves as Native but not as part of the four major Native nationalities (Cherokee, Chippewa, Navajo, and Sioux).

Ancestry groups by the total population

German 16.4% (49,836,146)
African American 12.2% (37,122,425)
Irish 11.8% (35,751,133)
Mexican 10.1% (30,731,943)
English 9.0% (27,403,063)
Italian 5.8% (17,566,693)
Polish 3.2% (9,835,459)
French 3.1% (9,326,180)
Dutch 1.6% (4,950,041)
Norwegian 1.5% (4,602,337)
Puerto Rican 1.5% (4,455,149)
Chinese 1.1% (3,294,615)
Filipino 0.8% (2,523,448)
Cuban 0.6% (1,690,061)
Local Native 0.5% (1,665,269)
Portuguese 0.5% (1,426,121)
Japanese 0.3% (817,103)
Navajo 0.1% (298,164)
Cherokee 0.1% (282,760)
Sioux <0.1% (119,236)
Chippewa <0.1% (115,036)

If we compare the American population by ancestry with the ethnic groups that live in Europe, it turns out that most Irish people currently live in the United States, not Ireland. Because Ireland has never recovered population-wise from the potato famine and following the mass emigration, their population peaked in 1845 and then decreased by over 50% before gradually growing to about 2/3 the historical peak.

Besides Scotland and Wales, there are also many Norwegians living in the United States. About 1/3 of the Norwegian population emigrated to America.

The United States population by ancestry relative to homeland population
Map of The U.S. population by ancestry relative to homeland population
Reddit user: 09_nations_

The maps explaining how immigration to America has changed over time you can find here.

Related posts:
Leading group by U.S. county (1990 – 2017)
Leading minority group by U.S. county (1990 – 2017)
American Indian Population by County (1990 – 2017)
U.S. Asian Population by County (1990 – 2017)
U.S. Black Population by County (1990 – 2017)
U.S. Hispanic Population by County (1990 – 2017)
U.S. Non-Hispanic White Population by County (1990 – 2017)
U.S. Population Density
Largest participating religious group (1906 – 2010)
Second largest participating religious group (1906 – 2010)

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