Aretha Franklin, photographed in 1977. Hulton Archive/Getty Images hide caption
The NPR 100
NPR presents the 100 of the most important American musical works of the 20th centuryJohn Coltrane. Evening Standard/Getty Images hide caption
Seminal American blues singer and songwriter Muddy Waters. Keystone/Getty Images hide caption
Earl Scruggs performs at the Stagecoach Music Festival in 2007. Karl Walter/Getty Images hide caption
Legendary American jazz pianist and singer Fats Domino. Express Newspapers/Getty Images hide caption
Woody Guthrie. Robin Carson/Courtesy of the Woody Guthrie Archives hide caption
American country music singer and guitarist Loretta Lynn performs on stage at the Grand Ole Opry, 1960s. Hulton Archive/Getty Images hide caption
Al Green, from the cover of his Greatest Hits album, first released in 1975. Courtesy of the artist hide caption
Kurt Cobain performs with Nirvana at a taping of the television program 'MTV Unplugged' in New York City, Novemeber 18, 1993. Frank Micelotta/Getty Images hide caption
George Gershwin in the 1930s. Courtesy of Wikimedia Commons hide caption
Songwriter and guitarist Bruce Springsteen. Monty Fresco/Getty Images hide caption
American blues singer Billie Holiday singing with an orchid in her hair. Hulton Archive/Getty Images hide caption
American singer, pianist and songwriter Ray Charles performs in concert. Hulton Archive/Getty Images hide caption
The Doors arrive at London Airport in 1968. Express/Getty Images hide caption
American jazz saxophonist Coleman Hawkins and jazz trumpeter Dizzy Gillespie in concert with the Cannonball Adderley Quintet, November 27th, 1960. Express/Getty Images hide caption
Bert Lahr (far right), Ray Bolger (back row, right), Judy Garland (sitting, right), composer Harold Arlen (sitting left), and various MGM and music publishing executives sing songs from the 1939 film musical 'The Wizard of Oz' around a microphone in the NBC radio studio, circa 1939. Hulton Archive/Getty Images hide caption
Buddy Holly, right, with his group The Crickets, Jerry Allison and Joe Mauldin. Keystone/Getty Images hide caption
The Ramones. Evening Standard/Getty Images hide caption
Rap pioneers the Sugarhill Gang (left to right: Wonder Mike, Master G and Big Bank Hank) perform live circa 1979. Michael Ochs Archives/Getty Images hide caption
American folk singer and activist Pete Seeger (left) adopted and helped popularize "We Shall Overcome" by teaching the song at rallies and protests. Here he sings with activists in Greenwood, Miss., in 1963. Adger Cowans/Getty Images hide caption
Elvis Presley, in an undated photo. Michael Ochs Archives/Getty Images hide caption