Given the widespread anti-Catholic sentiments in the US, why was the US so eager to allow a lot of Catholics to move to the US in the 19th and early 20th centuries? I know that the US had large-scale Catholic-phobia as late as 1928, when Al Smith's Catholicism cost him a lot of votes during his presidential run. However, this simply raises the question of why exactly the US let so many Catholics move into the country in the first place. I mean, Imperial Germany was also Catholic-phobic during this time but unlike the US it never opened its doors to large numbers of Catholic immigrants. Why was the US different?