<P> After World War II, new styles of electric blues became popular in cities such as Chicago, Memphis, Detroit and St. Louis . Electric blues used electric guitars, double bass (gradually replaced by bass guitar), drums, and harmonica (or "blues harp") played through a microphone and a PA system or an overdriven guitar amplifier . Chicago became a center for electric blues from 1948 on, when Muddy Waters recorded his first success, "I Can't Be Satisfied". Chicago blues is influenced to a large extent by Delta blues, because many performers had migrated from the Mississippi region . </P> <P> Howlin' Wolf, Muddy Waters, Willie Dixon and Jimmy Reed were all born in Mississippi and moved to Chicago during the Great Migration . Their style is characterized by the use of electric guitar, sometimes slide guitar, harmonica, and a rhythm section of bass and drums . The saxophonist J.T. Brown played in bands led by Elmore James and by J.B. Lenoir, but the saxophone was used as a backing instrument for rhythmic support more than as a lead instrument . </P> <P> Little Walter, Sonny Boy Williamson (Rice Miller) and Sonny Terry are well known harmonica (called "harp" by blues musicians) players of the early Chicago blues scene . Other harp players such as Big Walter Horton were also influential . Muddy Waters and Elmore James were known for their innovative use of slide electric guitar . Howlin' Wolf and Muddy Waters were known for their deep, "gravelly" voices . </P> <P> The bassist and prolific songwriter and composer Willie Dixon played a major role on the Chicago blues scene . He composed and wrote many standard blues songs of the period, such as "Hoochie Coochie Man", "I Just Want to Make Love to You" (both penned for Muddy Waters) and, "Wang Dang Doodle" and "Back Door Man" for Howlin' Wolf . Most artists of the Chicago blues style recorded for the Chicago - based Chess Records and Checker Records labels . Smaller blues labels of this era included Vee - Jay Records and J.O.B. Records . During the early 1950s, the dominating Chicago labels were challenged by Sam Phillips' Sun Records company in Memphis, which recorded B.B. King and Howlin' Wolf before he moved to Chicago in 1960 . After Phillips discovered Elvis Presley in 1954, the Sun label turned to the rapidly expanding white audience and started recording mostly rock' n' roll . </P>

When did the blues era start and end