With 13.5% of the population identifying as Irish, bars everywhere, and a parade that dates back to 1869, the Steel City is as close to Dublin anyone's gonna get in the US. Boston, which you likely thought would be first, came in second place, with 13.6% of Irish folks and the oldest parade in the running, established in 1737. In third (or "turd") place is the rather unlikely choice of Davenport, IA, where 13.1% of the residents are Irish, and Facebook hype is strong.
While Pennsylvania wins the list, with Philly (no. 5) giving the state two of the highest ranking cities in the top 10, Missouri also has two big cities in the ranking: Kansas City (no. 7), and St. Louis (no. 9). As for Chicago -- which famously dyes its river green every year -- that just made 10th place, with little Facebook hype, and only 6.9% of citizens of Irish heritage.