The Catholic Church in the United States began in the colonial era, but by the mid-1800's, most of the Spanish, French, and Mexican influences had institutionally and demographically faded, owing to the Louisiana Purchase (1803) and the Treaty of Guadalupe Hidalgo (1848). The former territories of France, Spain, Mexico and the domains of the Native Peoples at the time were then opened up to East Coast, Southern and mid-Western Americans, primarily Protestant, migrating westward. During this same period, the Catholic Church in the East and mid-West grew through immigration overseas, especially from Europe (Germany and Ireland at first, and in 1890-1914 from Italy, Poland and Eastern Europe.) In the nineteenth century the Church set up an elaborate infrastructure, based on diocese run by bi