Paul Simon wrote Bridge Over Troubled Water in 1969, and it became the title track of Simon & Garfunkel's final album as well as a hit single. Simon originally wrote just the first two very gospel-influenced verses; he was then persuaded to write a third ('Sail on, silver girl...'), which leads the song in a rather different direction.
Simon was said to have taken his inspiration from Oh Mary Don't You Weep, a song written by Claude Jeter for his gospel group The Swan Silvertones. Musically there's no similarity, but Jeter's song does include the line (spoken by Jesus), 'I'll be your bridge over deep water if you trust in my name'. Simon did later acknowledge his debt to Jeter. Bridge Over Troubled Water was usually sung solo by Art Garfunkel, who kept it in his repertoire after the duo split up
Elvis Presley picked up the song and made it a regular part of his live shows in the 1970s, his early background in gospel music clearly showing through. Aretha Franklin and Roberta Flack both released excellent versions in 1971, Aretha's very much gospel, Roberta's more meditative. The song also stood up well to Jimmy London's 1972 reggae treatment. It even survived (just about) as a disco hit by Linda Clifford in 1979. Johnny Cash, who recorded the song not long before his death in 2003, sang it with the feeling of someone who'd needed that bridge.
Gurt Lush Choir have borrowed the a capella arrangement written by Ali Orbaum for Bristol's Gasworks Choir, but there are sadly no YouTube performances of this as yet. However, here are three other very different choral arrangements that perfectly demonstrate the song's versatility: