^-- What she (right?) said.
It happens to be as big as it is in the U.S. (and Canada? New knowledge of the day for me) because...:
You had shitloads of Irish immigrants within the same timeframe as Swedes and people of a few other european nationalites immigrated into the states.
There was a rush over somewhere between 1820 and 1920 (off the top of my head) when the times got hard on mostly farmers in Europe...
and there was plenty of U.S. land deals available for immigrants at the time.
So it's just imported traditions from one of the larger nationality groups who emigrated from Europe.
