Who's Who an' Where? Ancestral Distribution in the USA

Here's a map I snagged from Wikipedia about ancestral population distribution.  Interestingly, German is the largest ancestral heritage in the United States, Irish is another major one, though you have to remember population density in this map.  Some of the most heavily populated areas in the United States are predominantly Irish even though geographically they don't cover as much area. (Click the image to enlarge it).