Since I tend to avoid the socially hostile binge-drinking festivities that often surround St. Patrick's Day in Chicago, I mark the occasion by 1) getting out of River North as fast as the CTA will take me 2) listening to "The Sick Bed of Cuchulainn," the most historically rich drinking song ever written 3) mapping. The fact that the most common ancestry where I grew up is "American," so migration patterns remain fascinating to me.

Below is a map of Chicago's Irish-American population by Census tract—those that declared primary or secondary Irish ancestry, according to data from the American Community Survey. The results are… not at all surprising, if you have even a passing familiarity with Chicago. Beverly and Mount Greenwood are home to the city's most densely Irish tracts (Beverly's also one of Chicago's picks for the best places to live in Chicago), followed by one tract in Canaryville that tops 40 percent. If Wrigleyville seems particularly active tonight, it's not (just) the bars—of all the near-er North Side, the tract that includes the field itself is the most Irish, at 25 percent.