US religious traditions are predominantly Judeo-Christian, and most Americans identify themselves as Protestants (of various denominations), Roman Catholics, or Jews. As of 1995, 163 million Americans, about 63% of the total population, reported affiliation with a religious group. The largest Christian denomination is the Roman Catholic Church, with 1995 membership estimated at 59.9 million in 19,787 local congregations with some 50,000 clergy. Immigration from Ireland, Italy, Eastern Europe, French Canada, and the Caribbean accounts for the predominance of Roman Catholicism in the Northeast, Northwest, and some parts of the Great Lakes region, while Hispanic traditions and more recent immigration from Mexico and other Latin American countries account for the historical importance of Roman Catholicism in California and throughout most of the sunbelt. More than any other US religious body, the Roman Catholic Church maintains an extensive network of parochial schools.
Jewish immigrants settled first in the Northeast, where the largest Jewish population remains; at last estimates, nearly 6 million Jews (or 3.7% of those reporting religious affiliation in the United States) were affiliated with over 3,400 local congregation served by 6,500 clergy.
According to reported statistics, 94,612,579 persons in the United States reported affiliation with a Protestant denomination. Baptists predominate below the Mason-Dixon line and west to Texas. By far the nation's largest Protestant group, the Southern Baptist Convention had 15,892,000 adherents by 1997 estimates; the American Baptist Churches in the USA claimed some 1,503,000 adherents in 1996. A concentration of Methodist groups extends westward in a band from Delaware to eastern Colorado; the largest of these groups, the United Methodist Church had 8,646,595 adherents. Lutheran denominations, reflecting in part the patterns of German and Scandinavian settlement, are most highly concentrated in the north-central states, especially Minnesota and the Dakotas. Two Lutheran synods, the Lutheran Church in America and the American Lutheran Church, merged in 1987 to form the Evangelical Lutheran Church in America, with more than 5,185,000 adherents in 1997. In June 1983, the two major Presbyterian churches, the northern-based United Presbyterian Church in the USA and the southern-based Presbyterian Church in the United States, formally merged as the Presbyterian Church (USA), ending a division that began with the Civil War. This group claimed 3,611,000 adherents in 1997. Other Protestant denominations and their estimated adherents (by year) include the Episcopal Church 2,365,000 (1996); Churches of Christ 1,800,000 (1997); and the United Church of Christ 1,438,000 (1997). One Christian group, the Church of Jesus Christ of Latter-Day Saints (Mormon), with 4,923,000 members (1997), was organized in New York in 1830 and, since migrating westward has played a leading role in Utah's political, economic, and religious life. Notable during the 1970s and early 1980s was a rise in the fundamentalist, evangelical, and Pentecostal movements. In the first half of the 1990s, Pentecostal churches reported 10,281,559 adherents, representing over 6% of the population reporting religious affiliation.
Several million Muslims followers of various Asian religious, a multiplicity of small Protestant groups, and a sizable number of cults also participate in US religious life.