This song was included on the band's fourth album and is a cover inspired by the original version by the African-American blues duet, Kansas Joe McCoy and Memphis Minnie from 1929.
The song talks about the consequences suffered by the African-American community, who lived in the lower part of the Mississippi River, when it overflowed in 1927 as a result of the intense rains that accumulated during that year. The great flood of the Mississippi River is considered a of the most destructive tragedies in the history of the United States, and which forced the African-American community to move to the western and northeastern areas of the country.
The Led Zeppelin cover transforms the upbeat blues version into a slower, darker song, which begins with a unique drum sound by using a pair of dynamic microphones hung on the third floor of a staircase, above the drums and later mixed to obtain a unique echo and resonance effect. Likewise, the harmonica and guitar were mixed to obtain an inverted echo effect, in addition to being slowed down to generate a muddier sound.
This technical complexity makes it quite difficult to play the song live, so they only performed it a couple of times on their first tours and it was not until the Rock And Roll Hall of Fame in 1995 that they performed it live again.
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