St. Patrick's Day by the Numbers. Everyone can be Irish for a day on March 17. In the U.S., St. Patrick's Day has evolved into a reason to celebrate your Irish heritage. On average, 13 million pints of Guinness are served on March 17. Chicago has a famous tradition of dyeing its river green. The tradition started in 1942, and takes 40 pounds of dye. Boston is a great place to celebrate with its annual parade. It is the most Irish city in the U.S., with 20.4% of its citizens are of Irish ancestry. 79% of celebrators plan to wear green.
