The Catholic Church has been a presence in the United States since the arrival of French and Spanish missionaries in the 16th and 17th centuries. The Spanish established a number of missions in what is now the western part of the United States; the most important French colony was New Orleans. Although they were a minority in the thirteen British colonies prior to the American Revolution, Catholics found ways to participate in communal forms of worship when no priest was available to celebrate Mass. John Carroll was appointed superior of the Mission of the United States of America in 1785. Four years later, Carroll was elected the first bishop in the United States; his diocese encompassed the entire country. The Catholic population of the United States began to grow during the first half of the 19th century primarily due to Irish and German immigration. Protestant America was often critical of the newcomers, believing one could not be a good Catholic and a good American at the same time. By 1850, Roman Catholicism was the largest denomination in the United States.
The number of Catholics arriving in the United States declined during the Civil War but began to increase after the cessation of hostilities. Catholic immigrants during the late 19th and early 20th centuries were primarily from southern and Eastern Europe, and they were not often welcomed by a church that was dominated by Irish and Irish American leaders. At the same time that the church was expanding its network of parishes, schools, and hospitals to meet the physical and spiritual needs of the new immigrants, other Catholics were determining how their church could speak to issues of social and economic justice. Dorothy Day, Father Charles Coughlin, and Monsignor John A. Ryan are three examples of practicing Catholics who believed that the principles of Catholicism could help to solve problems related to international relations, poverty, nuclear weapons, and the struggle between labor and capital.
In addition to changes resulting from suburbanization, the Second Vatican Council transformed Catholicism in the United States. Catholics experienced other changes as a decrease in the number of men and women entering religious life led to fewer priests and sisters staffing parochial schools and parishes. In the early decades of the 21st century, the church in the United States was trying to recover from the sexual abuse crisis. Visiting America in 2015, Pope Francis reminded Catholics of the important teachings of the church regarding poverty, justice, and climate change. It remains to be seen what impact his papacy will have on the future of Catholicism in the United States.
The Evolution of the Unitarian Model of the Catholic-Orthodox Dialogue in the Context of the Eastern Policy of the Holy See and the Second Vatican Council