Think about it. Picture it. Rewind any other 20-year chunk of 20th-century time. There’s no chance you would mistake a photograph or movie of Americans or an American city from 1972—giant sideburns, collars, and bell-bottoms, leisure suits and cigarettes, AMC Javelins and Matadors and Gremlins alongside Dodge Demons, Swingers, Plymouth Dusters, and Scamps—with images from 1992. Time-travel back another 20 years, before rock ’n’ roll and the Pill and Vietnam, when both sexes wore hats and cars were big and bulbous with late-moderne fenders and fins—again, unmistakably different, 1952 from 1972. You can keep doing it and see that the characteristic surfaces and sounds of each historical moment are absolutely distinct from those of 20 years earlier or later: the clothes, the hair, the cars, the advertising—all of it. It’s even true of the 19th century: practically no respectable American man wore a beard before the 1850s, for instance, but beards were almost obligatory in the 1870s, and then disappeared again by 1900. The modern sensibility has been defined by brief stylistic shelf lives, our minds trained to register the recent past as old-fashioned.
