NJ definitely has a very large Catholic population. Just about everyone I knew growing up in NJ was Catholic. My town had three large catholic high schools in addition to two large public high schools. Just about every town has its own Catholic HS in my county.
en.wikipedia.org/wiki/New_Jersey#Religion
I remember when I was in middle school (public school) we had to cancel several school soccer practices and a game due to Confirmation practice and the actual Confirmation since roughly 18/20 kids on the team were Catholic. The same applied for the other school sports in that season. The other public middle schools in my town had to do the same. So that is a good example of how large the catholic population was in my town.