The Washington Post has come out with a map that shows the dominant racial ancestry in the United States' 3144 counties. Some results are not surprising: Did you know that there are a lot of Irish people in Boston? It's not a surprise to see African Americans dominate the South and Mexicans dominate the border counties.
This map makes white ethnic origins look homogeneous as well, with people of German ancestry dominating from the Midwest to Northern California. I find the ethnic diversity in Hawaii especially interesting, with a mix of dominance by Filipinos, Japanese, and native Hawaiians. As a bonus, this map correlates with Colin Woodward's representation of the 11 nations within the United States of America, which is highly fascinating.
Image via Washington Post.