In an indication of the growing religious organization and visibility of the nation's Muslims, the number of mosques in the United States increased by about 25 percent in six years, to more than 1,200, a study sponsored by four American Islamic organizations has found.
The findings of the Mosque Study Project 2000, whose report is titled, "The Mosque in America: A National Portrait," were released yesterday, published by the Council on American-Islamic Relations, a nonprofit advocacy organization. A similar study in 1994 found 962 mosques in the country.
Recent estimates of the number of Muslims in the United States have varied widely. The new study estimated the total at between six million and seven million, arriving at those numbers through calculations based on the average number of Muslims with whom mosques reported some connection.
If that estimate is correct, then the American Muslim population at least equals the commonly accepted figure of six million Jews in the United States. But John Esposito, director of the Center for Muslim- Christian Understanding at Georgetown University, said that until more information was collected, he would estimate the Muslim population to be somewhat lower.
"It's reasonable to talk about four to six million," Professor Esposito said. But "it's going to be pushing up," he added, citing both continuing immigration and the relatively large size of many Muslim families.
"If it's not the case now," he said, "then within a matter of decades Islam will be the second-largest religion in America."
The study also found that a large majority of mosques were in cities and suburbs, that attendance was overwhelmingly male and that worshipers were ethnically diverse: one-third are South Asian, 30 percent African-American, 25 percent Arab. It also said nearly all mosques used English as the main language, or one of the main languages, for sermons at Friday prayers.
Twenty percent of mosques have Islamic schools of full-time general study for children, and 70 percent provide charitable assistance for the poor, the study reported.
Research for the study was supported by the council and three other organizations: the Islamic Society of North America, the ministry of Imam W. Deen Mohammed and the Islamic Circle of North America.
It was done in conjunction with a larger study of religion in the United States, organized by Hartford Seminary's Institute for Religious Research. Twenty-six religious groups are participating, each having done research among its members drawing on a common set of questions.
To estimate the number of mosques, the researchers used different lists of Muslim houses of worship around the nation, eliminated duplicates and confirmed the existence of individual mosques by telephone, said one participant, Ihsan Bagby, chairman of the department of international relations at Shaw University in Raleigh, N.C.
Dr. Bagby said the researchers had then conducted detailed telephone interviews with representatives of more than 400 mosques for the study, which has been posted on the council's Web site, www .cair-net.org.
"I think this is a solid list," Dr. Bagby said of the estimated number of mosques. He added, however, that some "smaller, newer mosques" recently established by immigrants might have gone uncounted.