FACTBOX: America's Roman Catholic population

(Reuters) - Once solidly Irish, Italian and Polish, the U.S. Roman Catholic Church, the largest Christian denomination in the country, has become increasingly Hispanic in recent years.

Like other mainline denominations it is also losing members to competing faiths such as evangelical Protestant churches.

Following are some facts and figures about the U.S. Catholic population, which will greet Pope Benedict when he visits the United States from April 15 to 20.

- According to a recent nationwide survey by the Pew Forum on Religion and Public Life, 23.9 percent of the adult U.S. population identifies itself as Catholic. This tallies with estimates by the U.S. Catholic Church itself.

- Since the early 1970s the percentage of the population counting itself as Catholic has remained stable at around 25 percent. But according to Pew, no other major faith has experienced greater net losses with 31.4 percent of U.S. adults saying they were raised Catholic and about one in 10 describing themselves as former Catholics.

- In the face of these losses the Church has maintained its share of the U.S. population by winning its own converts but mostly through immigration, especially from Latin America. The United States Conference of Catholic Bishops says that about 39 percent of U.S. Catholics are Hispanic.

- The USCCB also says that since 1960, 71 percent of U.S. Catholic population growth has been Hispanic and that by the second decade of the 21st century, more than 50 percent of U.S. Catholics will likely be Hispanic.

- The USCCB estimates that there are 2.3 million African American Catholics. There is also a growing population of Vietnamese Catholics in areas like north Texas.

- The U.S. Northeast remains one of the centers of American Catholicism, with 29 percent of all adults there belonging to the faith.

- One indicator of the resiliency of Catholicism in any country is the Mass attendance rate among the flock. According to a 2007 survey by Georgetown University’s Center for Applied Research in the Apostolate, about one fifth of U.S. Catholics attend Mass at least once a week while 11 percent go almost every week.

(Sources: Pew Forum on Religion & Public Life; United States Conference of Catholic Bishops; Reuters; Center for Applied Research in the Apostolate)

Compiled by Ed Stoddard; Editing by Mike Conlon and Xavier Briand