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 on March 17, 1762, in New York City, featuring Irish soldiers serving in the English military. This parade became an annual event, with President Harry Truman attending in 1948. Congress proclaimed March as Irish-American Heritage Month in 1995; President Obama issued a proclamation commemorating the month of March "Irish-American Heritage Month."
The President stated, "From the earliest days of our Republic, the Irish have overcome discrimination and carved out a place for themselves in the American story. Through hard work, perseverance, and patriotism, women and men of Irish descent have given their brawn, brains, and blood to make and remake this Nation -- pulling it westward, pushing it skyward, and moving it forward.

The following is courtesy of the U.S. Census Bureau:
Population Distribution- Number of U.S. residents who claimed Irish ancestry in 2009: 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.
Number of Irish-born U.S. residents in 2009- 122,000. Those from Ireland are much older (a median of 60 years old) and have a higher median household income ($56,158) than U.S. residents as a whole (37 years and $50,221, respectively).
Percent of Massachusetts residents who were of Irish ancestry in 2009- 24 percent. This compares with a rate of 12 percent for the nation as a whole.
Irish-Americans Today
Percentage of people of Irish ancestry, 25 or older, who had a bachelor’s degree or higher- 32 percent. In addition, 92 percent of Irish-Americans in this age group had at least a high school diploma. For the nation as a whole, the corresponding rates were 28 percent and 85 percent respectively.
Median income for households headed by an Irish-American- $56,383. This is higher than the $50,221 for all households. In addition, 10 percent of people of Irish ancestry were in poverty, lower than the rate of 14 percent for all Americans.
Percentage of employed civilian Irish-Americans 16 or older who worked in management, professional and related occupations: 40 percent. Additionally, 27 percent worked in sales and office occupations; 16 percent in service occupations; 9 percent in production, transportation and material moving occupations; and 8 percent in construction, extraction, maintenance and repair occupations.
Percentage of householders of Irish ancestry who owned the home in which they live, with the remainder renting- 70 percent. For the nation as a whole, the homeownership rate was 66 percent.
The Celebration
U.S. beef and cabbage production, respectively, in pounds, in 2009- 26.1 billion and 2.3 billion. Corned beef and cabbage is a traditional St. Patrick’s Day dish in the United States.
Source: 2009 American Community Survey