St. Paddy's Day question: How Irish is your county?

Even those who claim no Irish ancestry wear green on March 17, and join in the day's celebrations, promoting the saying, "Everyone's Irish on Saint Patrick's Day." But just how Irish is your county? Here's a map from Jed Kolko, chief economist for Trulia Trends, a real-estate data site. (Click on map for larger version; click here for interactive version that can show specific percentages for each county.)

The data come from the Census Bureau's American Community Survey, its year-round poll of Americans, which asks them their "primary ancestry." That is claimed by 22 million Americans, or 7.2 percent of the population. "Another 13.5 million Americans claim at least some Irish ancestry, bringing the total to 35.5 million Americans — 11.6 percent of the population — with at least partial Irish ancestry," Kolko writes.