The numbers of Roman Catholics are expanding in the South and West. Evangelicals are growing everywhere, and there are fewer Muslims than everyone thought.
These are some of the findings in the most complete religious survey of the United States, and one of the most surprising is that Muslims, many of whom attend mosque services, number just 1.6 million, far below the estimates of 7 million by Islamic groups.
The figures from the Religious Congregations and Membership survey of 2000 are based on the Muslims affiliated with America's more than 1,000 mosques, not the total number. The finding touched a sensitive nerve on the debate over the presence and influence of U.S. Muslims.
"Unfortunately, not all Muslims attend a mosque," says Ibrahim Hooper, spokesman for the Council on American-Islamic Relations.
He said many have taken the 1.6 million to stand for the number of all Muslims, and in fact other national surveys have argued that the U.S. Muslim population is below 2 million. Mr. Hooper says the 1.6 million number for mosque affiliation "still sustains our 7 million figure" of all adherents to Islam.
"We believe this is a very reliable picture of American affiliation to local congregations," said Dale E. Jones, a statistician with the Church of the Nazarene and a chairman of the project.
"It's not like a national poll, but more like going to the nation's political wards and asking how many voting people they had," he said in an interview yesterday. The entire report is to be released tomorrow.
The every-decade survey, a project since 1966 of the Glenmary Home Missioners, a Catholic organization in Cincinnati, is considered the most reliable data on religious affiliation down to the county level.
The reports were collected from 149 of 258 known religious bodies in the United States, and evaluated carefully in cooperation with the Association of Statisticians of American Religious Bodies.
As expected, the Catholic Church has the largest adherence nationally; the state of Utah with its Mormon preponderance has the highest churchgoing rates; and Oregon, which is notoriously secular, has the lowest religious participation.
"There are now more Catholics in the West than in the Midwest," said Clifford Grammich of the Glenmary Research Center.
Catholic parishes in the West and South are growing faster than elsewhere, often by a third, he said. "The Church may have to shift more of its institutional resources to meet this growth, or give more attention to mission needs" there.
Most growth in religious affiliations may be due to Hispanic immigration and birth rates: Of the 11 million new adherents reported during the past decade by 87 of the largest groups, 9 million were Catholics.
All Protestants outnumber Catholics nationally, however, and they make up the largest religious grouping in 2,493 of the nation's 3,141 counties.
One reason for the cooperative census is to find out at the county and state levels how much of the population is "unclaimed" by religious groups and thus fertile ground for faith organizations to reach out.
Mr. Jones said that in the past decade, for example, the typical low-attendance states, such as Washington, have shown a spurt in "claimed" population, perhaps because of evangelism there during the 1990s.
"An awful lot of Western counties have shown gains in claimed people," he said.
Overall, according to this census sample, 50.2 percent of the nation's 280 million citizens are claimed by a local congregation.
In national polls, by contrast, more than seven in 10 Americans claim affiliation and nine in 10 profess belief in God.
The survey also has punctured the folk wisdom that rural Americans are more pious than urban ones. "There is really no difference between the metro and non-metro areas on how many are claimed by congregations," which is about 50 percent "claimed," Mr. Jones said.
But nationally, affiliation has dropped by a few percentage points in 10 years. Mr. Jones said this suggests a loss of denominational identity or feeling that "you can be a good religious person without belonging to a congregation."
For example, 71 percent of U.S. counties have not shown gains in "claimed" people in the past decade.
That decline is seen particularly in the more liberal Protestant "mainline," with United Methodists losing nearly 7 percent, the Episcopal Church 5 percent, and the Evangelical Lutherans more than 2 percent of their local memberships.
Though the survey sample is large enough to be representative, it had no way to gather data from "small independent churches" or the new "megachurches."
The eight historic black denominations, such as the National Baptist Convention and the African Methodist Episcopal Church, declined to participate.
Gathering good statistics is difficult, Mr. Jones said, and like many churches, the black denominations have lacked firm estimates. What the survey did show, he said, is that more black Americans are joining churches with European origins.
Utah, with its large Church of Jesus Christ of Latter-day Saints membership, for the second decade running had the highest rate of church affiliation at 74.7 percent. The District of Columbia is close behind with 73 percent.
By comparison, adherence in Oregon is 31 percent, and it is 33 percent in Washington.
The District of Columbia, moreover, boasts the third-largest number of congregations for a metro area.