Why did many Catholics live in Pennsylvania?

Answer 1

It was't. It was founded as a haven for European Quakers and the Frame of Government allowed any religion that was monotheistic to enter and to become a citizen. The German Catholics found refuge free from prosecution by the Protestant revival. Lutherans in Catholic areas found refuge in the new world.

Religion shuffles world politics and world politics shuffles geography. Papal decree divided South America between Spain and the Portugese. Economics brought together a nation without religious boundaries and such is the "Freedom of Religion and the Freedom From Religion an essential part of American heritage.

Answer 2

According to the census in 1990, there were (at that time) 3,675,250 Catholics in Pennsylvania, or about a third of the population. Pennsylvania has the ninth largest pecentage of Catholics of the states in the United States.