Jazz originated in New Orleans early in the 20th century, bringing together elements from ragtime, slave songs, and brass bands. One of the distinguishing elements of jazz was its fluidity: in live performances, the musicians would almost never play a song the same way twice but would improvise variations on its notes and words. Jazz was the reigning popular American music from the 1920s through the 1940s. In the 1930s and 1940s, the most popular form of jazz was "big band swing," so called after large ensembles conducted by the likes of Glenn Miller and William "Count" Basie.
In the late 1940s, a new, more cerebral form of mostly instrumental jazz, called be-bop, began to attract audiences. Rhythm & blues was a combination of jazz and other “race” music with the lyrical content, sonic gestures and format of the blues. The epoch of rhythm and blues spans the late 1940s to the early 1960s. The melding of rhythm & blues with country and western music in the mid-1950s gave birth to rock and roll. In the mid-1960s, rhythm and blues would become soul music. In the 1970s, many jazz musicians experimented with electronic instruments and created a blend of rock and jazz called fusion.
Due to its diversity, popular music in the United States today challenges simple description. The history of popular music in the 1970s and '80s is basically that of rock music which has grown to include hundreds of musical styles. New styles such as folk, salsa, new wave, funk, reggae, heavy metal, acid rock, punk rock, rap, hip hop, acid jazz and world music have developed. Country rock, a fusion of country and western and rock 'n' roll, grew popular in the 1970s. A blend of rhythm and blues and gospel music came to be known as soul. Disco, a repetitive dance music, and rap music are direct descendants. Rap developed in the mid-1970s among African-American and Hispanic performers in New York City. It generally consists of chanted, often improvised, street poetry usually accompanied by disco or funk music. The 1990s saw the birth of alternative music or grunge. Techno, a style of dance music that gained popularity in the 1990s, combines computer-generated, disco like rhythms with digital samples.
Pop music plays a major role in the American entertainment industry, with particular help these days from female vocalists who dominate the radio, such as Sheryl Crow (shades of the “California rock” style of the old band The Eagles) and Lucinda Williams (a fusion of blues, country, and rock). Older styles of pop continue to be a strong part of the American musical landscape. Sounds from even earlier in rock history are never far away; the group Sugar Ray incorporates so many elements from old rock styles that the result is both nostalgic and refreshing. Newcomer Norah Jones, who in 2003 received all five Grammy Awards she was nominated for, is an intimate singer who proves the vitality of the softer rock beat and meaningful lyrics. The pop music field is still spreading its stylistic influences around a world that has never lost its appetite for the latest American sounds and stars.