This sounds like a foaf story, but my friend Sue got an e-mail from her daughter-in-law whose friend's husband Jim Linderman of Grand Rapids, Michigan, donated a collection of photographs of river baptisms (1st image, I added the 2nd and 3rd), one over a yard long.
Who: The tradition flourished from 1880 to 1930 among traditional Protestants. Charismatic preachers led the ceremony before entire fundamentalist rural communities.
What: "Take Me To the Water"
When: The donor will be there for the opening of the exhibit Thursday, 1/20/11. Linderman describes the collection, "Over the course of 10 years, I collected every photograph I could find of people participating in the ritual of immersion baptism. Initially, I found my baptism photos at flea markets and such. If I spotted one while browsing through boxes and baskets of photographs, I treated it like a prize and filed it away at home..."
Where: International Center of Photography in New York City (please contact ICP for details)
Why: The rite of baptism signified purity or cleansing from sin and devotion to God. In the Old Testament (John 1:33), John was directed by God to baptize those who accepted his message.
How: I paraphrase an article by Annie Staten and Susan Roach:
"As late as the 1950s, outdoor baptism was common. Even though the majority of churches had indoor baptismal pools, some chose to maintain the earlier, natural setting for this rite of passage, a symbolic ritual purification and initiation. Baptisms were generally held during the summer or early fall so the water would be warm enough. A 2-week-long revival meeting featuring prayer meetings and a guest minister would be followed by an outdoor baptism. A suitable spot in waist-deep water was chosen and the participants were lined up by age and clothed in traditional robes, and the service (hymns, scripture reading, and prayer) was begun. With sermons before and after, the minister baptizes the candidates one by one with a ritual statement, and immersed them. They were brought out of the water with embraces, songs, and applause, and helped to dry off. Inside the church, they are administratively pledged into the congregation, and they remove their headgear."