Pentecostalism, the Christian fundamentalist movement found worldwide, was born in Los Angeles early in the 20th Century. Historians trace the movement to William J. Seymour (died 1929), an African-American preacher who moved to Los Angeles from Texas in 1906. He founded the Azusa Street Mission from where he promoted the style of worship characterized by "speaking in tongues." Most of his followers were white. The movement led to the first rift over the style of worship in a mainline church when the congregation of St. Mark's Episcopal Church in Van Nuys split over the issue in 1960. An estimated 75 million people are believed to currently adhere to the Pentecostal (or charismatic) form of worship.
Source: Los Angeles A to Z by Leonard & Dale Pitt (University of California Press).