World War II made for massive changes not only in global politics and population but also in all aspects of culture throughout the world. To speak only of music, we have traced the radical developments of avant-garde music in its second phase, and noted the dissolution of the big jazz bands in America as well as the increasing complexity of our musical theater. And while popular song continued to flourish after World War II, it was a new kind of popular song, with less emphasis on melody and more on rhythm — or, more exactly, with a heavy emphasis on music’s meter. By the middle of the 1950s the new style took a name that captured this compelling rhythm: rock’n’roll. Later, in the 1960s, the name of choice was shortened to rock. Teenagers went wild. Their parents, reacting much as parents had thirty years earlier in the face of jazz, bemoaned the demise of civil culture and decent society.

Nevertheless, rock endured and evolved — in fact, it positively burgeoned. Its explosive development from 1955 to 1970 and its reinvention in the following decades have put rock on a historical par with jazz. If jazz can claim to be America’s most distinctive contribution to world art from the first half of the twentieth century, rock can make similar claims for the second half. Today the development of global pop, discussed in Global Perspectives on page 410, depends on various styles of American-derived rock more than on any other musical idiom.