Agree that at the federal level the RC was not dominant, and 80% of the WHOLE USA was not RC.  However, RCs were concentrated in the NE and some parts of the mid-West, and the church was dominant in the society.  I grew up in suburban Boston in the 50s and 60s, and AB ( and later Cardinal Cushing) was next to God.  He and the church were very influential politically. I knew the name of  Cushing, but I didn't know who was the governor.  I also remember how politically influential Cardinal Spellman was, both in NYC and at the national level.