Which group suffered the most from Anti-Catholic sentiment in the US during the 1800s?

Irish Catholics were the group that suffered the most from Anti-Catholic sentiment in the United States during the 1800s. As large numbers of Irish immigrants arrived, especially during the Great Famine in the 1840s, they faced intense discrimination and hostility from nativist groups who viewed them as a threat to American values and Protestant dominance. This sentiment often manifested in riots, violence, and the establishment of anti-immigrant organizations like the Know-Nothing Party. The pervasive prejudice against Irish Catholics contributed to their marginalization and social struggles during this period.