LOUIS ARMSTRONG
(1901–1971)
“Satchmo” (as he loved to be called) didn’t invent jazz, but it might have sounded unimaginably different without him. The bastard son of a sometime prostitute, Armstrong learned to play cornet in a New Orleans home for “colored waifs.” Having mastered the ensemble style of early jazz, he reshaped it in his own expansive image, shifting the emphasis from group improvisation to the virtuoso solo. No less significant were his genial, gravel-voiced vocals, which laid the foundation for all subsequent pop singing. Bing Crosby called him “the beginning and end of music in America.”

GEORGE GERSHWIN
(1898–1937)
Of all the inspired artists who created what is now called the Great American Songbook, it was Gershwin who did the most to infuse it with the quintessentially American sounds of ragtime and jazz. Working in tandem with his brother and lyricist Ira, he galvanized Broadway (and, later, Hollywood) with soon-to-be-standards like “I Got Rhythm” and “Someone to Watch Over Me.” At the same time, he produced a series of pop-flavored concert works, starting with Rhapsody in Blue, in which he pioneered the crossover genre, and in Porgy and Bess he tore down the wall that had separated opera from musical comedy.

AARON COPLAND
(1900–1990)
Before Copland came along, American classical musicians were struggling to forge their own distinctive stylistic identity. Attracted by the spare lucidity of Igor Stravinsky’s neoclassicism, the open-eared experimental approach of Charles Ives, and the off-center rhythms of jazz, Copland turned his back on nineteenth-century European Romanticism and replaced it with a spaciously lyrical, rhythmically vital style that at once evoked the hum and buzz of urban life and the wide-open expanses of the prairie. In such ballet scores as Billy the Kid, Rodeo, and Appalachian Spring, he all but single-handedly invented the sound of modern American classical music.

ELVIS PRESLEY
(1935–1977)
By fusing black rhythm and blues with white country (his first single had an R&B song on one side and a bluegrass tune on the other), Presley became the central figure in the great transformation that replaced Gershwin-style pop songs with rock and roll as the lingua franca of American popular music. Though he degenerated over time into the drug-sodden, chronically obese “fat Elvis” of countless cruel jokes, his sex-charged TV appearances and films of the ’50s made him the No. 1 teen idol of the buttoned-down Eisenhower era, and he set a benchmark for renown that today’s rock stars still strive to surpass.

BOB DYLAN
(1941)
American folk music was enjoying a short-lived spurt of popularity in the early 1960s when Dylan first emerged as a top protest singer with “Blowin’ in the Wind” and “The Times They Are A-Changin’.” Then he stunned his contemporaries by unexpectedly retrofitting himself as a hard-charging electric rocker whose lyrics were complex and ambiguous to a degree previously unknown in American popular song. Nor was this the only stylistic rabbit Dylan pulled out of his hat: he later embraced country music on his albums John Wesley Harding and Nashville Skyline. No one has done more to define the place of the singer-songwriter in contemporary pop.