The veteran saying that on St. Patrick's Day everyone is Irish is especially valid in Boston,a large proportion of whose residents, police, or firemen and other officials are of Irish descent. Boston is so Irish that not only is it's current mayor of Irish descent (Marty Walsh),but also even its basketball team has an Irish name and mascot - The Celtics with their Lucky Leprechaun. Boston is proud of its Irish heritage, which it displays for all the world to see in its annual St. Patrick's Day Parade.
Source: cbslocal.com