St. Patrick's Day in the United States is a celebration of immigrants. Immigrants who wouldn't pass the Krikorian Criteria. It is not a state-recognized, legal holiday in most places. Instead it is an outgrowth of American civil society.
The first observance occurred was in 1737 when the Charitable Irish Society of Boston organized a gathering to honor its homeland. The group was active in providing temporary loans and assistance to Irish immigrants and acting as a network for helping new arrivals find work.
These types of civil associations were a very important part of early American history - privately supplying club goods and insurance to a wide variety of ethnic, religious, and secular groups. This rich tapestry of civic life gave people space to exercise the art of association and learn to live in a dynamic world populated by people unlike themselves. It was in these spaces between the family and government where people could develop their own capabilities to diagnose social problems and initiate action aimed at mitigating problems particular to their time and place.
Voluntary society in associations and markets is what Richard Cornuelle advanced as necessary for the functioning of a free and responsible citizenry. He termed this an "unfinished revolution" that sought to recover the confidence of individuals to exercise control over themselves and their communities, and resist using the state to try to fix problems.
People across the country will be celebrating today the legacy of a relatively more open boarders immigration policy of an earlier period. Between 1820 to 1860, roughly 2 million Irish arrived in the US, most fleeing the famine ravaging Ireland. They came poor, uneducated, and facing prejudice and discrimination. The lesson that this experiment was a strong net gain for America hopefully isn't lost amongst the fearmongering of politicians or the abundance of green beer.