Swamp blues is a type of Louisiana blues that developed around Baton Rouge in the 1950s and 1960s. It generally has a slow tempo and incorporates influences from other genres, particularly zydeco and Cajun. Its most successful proponents included Slim Harpo and Lightnin' Slim, who enjoyed national rhythm and blues hits and whose work was frequently covered by bands in the British Invasion.
Swamp blues has a laid-back, slow tempo, and generally is a more rhythmic variation of Louisiana blues, incorporating influences from New Orleans blues, zydeco, soul music and Cajun music. It is characterized by simple but effective guitar work and is heavily influenced by the boogie patterns used on Jimmy Reed records and the work of Lightnin' Hopkins and Muddy Waters. The sound of swamp blues was characterized by "eerie echo, shuffle beats, tremolo guitars, searing harmonica and sparse percussion".
Swamp blues originated in Baton Rouge, and was particularly associated with record producer J. D. "Jay" Miller. In the 1950s, Miller recorded many blues artists around the city, distributing their recordings through Excello Records in Nashville, Tennessee. The most successful and influential artist with whom he worked was guitarist and harmonica player Slim Harpo. Other major artists included Lightnin' Slim, Lazy Lester, Silas Hogan, Lonesome Sundown, and piano player Katie Webster. A number of their tracks, particularly those of Slim Harpo, were covered by British Invasion bands, including the Rolling Stones, The Kinks and the Yardbirds. The popularity of the genre faded in the 1970s, with many swamp bluesmen turning to zydeco which remained popular with black audiences.