Originally a religious holiday to honor St. Patrick, who introduced Christianity to Ireland in the fifth century, St. Patrick’s Day has evolved into a celebration for all things Irish.

The world’s first St. Patrick’s Day parade occurred March 17, 1762, in New York City, featuring Irish soldiers serving in the English military. This parade became an annual event, with President Harry S Truman attending in 1948.

Congress proclaimed March as Irish-American Heritage Month in 1995.

The number of U.S. residents who claimed Irish ancestry in 2009 was 36.9 million. This number was more than eight times the population of Ireland itself (4.5 million).

Irish was the nation’s second most frequently reported ancestry, trailing only German, in 2009 reports.

Twenty-four percent of Massachusetts’ residents in 2009 said they were of Irish ancestry. This compares with a rate of 12 percent for the nation as a whole.