AncestryMaps.com has tabulated United States census data for all ancestries.  We have used this data to create colorful maps that depict population clusters for any particular ancestral group at the county and zip code level.  We have posted maps for each ancestry group here for your viewing. 

These informative maps indicate where in the USA specific groups are predominant.  The maps are color-coded by percentages.  The darker shade that a county appears on the map, the higher percentage that particular ancestry.  For example, let's say you wanted to find which county in the US has the highest percentage of people with an English ancestry.  You simply click on the "View Maps" button above.  This will open a new page with all the ancestries surveyed in the US Census (each ancestry has it's country flag displayed next to it).  You would then scroll down the page and click on "English" to open it's respective map which displays all the counties in the US, color-coded according to the percentage of people with English ancestry.  You can then click on any state to "zoom-in" on that particular state to view ancestry percentages by zip code for that particular state.  For each map you can scroll down to the bottom of the map to view a legend depicting the actual percentage represented by each different color shade.  In addition, each state map lists the top 10 zip codes and their respective towns for each ancestry and each county map lists the top 10 counties.   AncestryMaps.com is best viewed with 1280x1084 resolution