The Catholic Church teaches that it is the one true church founded by Jesus Christ, that its bishops are the successors of Christ's apostles, and that the Pope is the successor to Saint Peter. The Church maintains that the doctrine on faith and morals that it presents as definitive is infallible. The Latin Church, the autonomous Eastern Catholic Churches and religious communities such as the Jesuits, mendicant orders and enclosed monastic orders reflect the variety of theological emphases within the Church. [Wikipedia]
Catholic settlers who came to America were primarily from southern Europe and Ireland. They met with considerable persecution in the States because of their "papist beliefs." Likewise, a big part of the clash between the native Spaniards and Mexicans in what would become Texas, the Southwestern and Western US, was as much a clash between Catholic and Protestant as it was between cultures.
My Catholic roots are fairly typical. My McHugh family came to America from County Donegal, Ireland during the 1830s looking for work in the coal mines of Pennsylvania. NW Illinois, SW Wisconsin, Chicago and finally Indianapolis were stopovers. County Cork native Catherine O'Neil arrived in the US in 1852, making Indiana her primary home.
Until I found the marriage between Baden-born John Wagner and Catherine Laubscher, I was fairly certain that they were German Catholics. Their daughter, Louisa married James McHugh. The couple was married in the German Reformed Church in Philadelphia in 1841.
My grandfather, after being reared in a devout Catholic home, left it to his four children to choose their own path. To the best of my knowledge, none of the four remained Catholic.