they have way cool interactive maps.
Here's one showing the foreign-born population by county. The years go back to 1880, and you can set the filter to look at just one country of origin.
Just in case you were wondering, Miami-Dade and Queens are each approximately 50% foreign-born and in each the predominant group is from Latin America.
h/t Global Sociology Blog, where you can also find maps of corruption and government spending around the world.