"The practice of honoring St. Patrick on March 17, traditionally understood as the day of his death (c. 493) at Downpatrick in County Down, is a tradition that comes from old Ireland. For centuries the people of Ireland marked the day as a solemn religious event, perhaps wearing green, sporting a shamrock, and attending mass, but little more. No one knows for sure when the first commemoration of St. Patrick's Day in America took place. One of the earliest references is to the establishment of the Charitable Irish Society, founded on St. Patrick's Day in Boston in 1737. Another early celebration took place in New York City in 1762, when an Irishman named John Marshall held a party in his house. Although little is known of Marshall's party, it is understood that his guests marched as a body to his house to mark St. Patrick's Day, thus forming an unofficial 'parade.' The first recorded true parade took place in 1766 in New York when local military units, including some Irish soldiers in the British army, marched at dawn from house to house of the leading Irish citizens of the city. With few exceptions, the parade in New York has been held every year since 1766. Thus was a tradition born - an American tradition only recently adopted in Ireland itself."Thus, thanks hanks to Irish-American Protestants, St. Patrick's Day became secularized rather than, as in Ireland, considered a day of holy obligation. In fact, until the 1970s the bars in Dublin were closed on March 17.
Early, groups such as the Hibernians, the Friendly Sons of Saint Patrick, and Irish Aid societies sprung up in America as a reflection of Irish loyalty and concern for Irish immigrants.
The idea spread. For example, on March 17, 1812, in Savannah GA, thirteen men founded the Hibernian Society dedicated to aiding destitute Irish immigrants, largely Catholic. A few months later, the group, now up to 44 members, adopted a constitution and the motto, "non sibi sed alis" (not for ourselves, but for others). Not one charter member was a Catholic. One year later, on March 17, the group marched in procession to a Presbyterian church for a service and oration.