Let’s get one thing straight: Corned beef and cabbage is not a traditional Irish meal.
The dish evolved among Irish American immigrants, not in the old country. How corned beef became associated with St. Patrick’s Day has more to do with the fact that it was an inexpensive cut of beef that was brined for preservation (and to counter any off-flavors), a technique Irish butchers learned from their Jewish neighbors.
While the citizens of Ireland have been observing March 17, the Catholic feast day of St. Patrick, since around the 10th century, the first St. Patrick’s Day parade was organized by an Irish vicar in 1601 in what is now Florida.
More than a century later, homesick Irish soldiers serving in the English military marked the day in New York City with a festive parade that drew thousands, and enthusiasm soon spread to Boston, St. Louis, Chicago and on. Within the next decade, these parades drew immigrant families from different countries — Italy, Germany, Spain — in solidarity with the Irish, all as American citizens.