Cities have always contained flexible, temporary elements that allow for special events, emergencies, wars, disasters, or mass migrations. What distinguishes American urbanism is the speed with which a modern, industrial metropolis like Chicago, New York, or Detroit could pop-up and then shrink, or even disappear. Indeed, the history of American urbanism can be understood as a history of pop-ups at different scales. » The relatively small population of the continent and ease of migration within a single large country have meant that Americans are perpetually on the move, relocating, on average, once every seven years. American cities have grown and shrunk with each shift in government or commercial policy favoring shipping, canals, railways, roads, airways, or airwaves. The public space of the nation seems to be constantly morphing, with ghost towns and dead malls littering the continent.

Americans have always had to adjust at a personal level to these shifts, seeking communal solutions to common problems through associations of various kinds based on particular issues. This self-help, do-it-yourself, communal tradition, often shielded by labor, academic, or religious freedoms, provided the background to such grassroots efforts as the Civil Rights, anti-war, and pro-democracy movements of the 1960s and 1970s. At Woodstock, the pop-up instant city, rock-and-roll provided the anthems for the nomadic youth culture of the period. Meanwhile, the streets and squares of San Francisco and other metropolises were the stage for marches and public protests.

The political pop-ups of the 1960s sought to address the faults of the emerging consumer society of the 1950s, itself a pop-up culture fueled by the excess industrial capacity and oil production created by the previous decade’s war effort. During World War II, workers in Seattle lived in mobile homes around new aircraft factories and shopped at temporary, wood-framed, proto­type shopping malls. Young architects such as Victor Gruen, who designed many of these open-air mini-malls, went on to develop this new type of public space across America. Wood-framed buildings housed the first McDonald’s on the commercial strips that popped up to serve the massive industrial production line housing tracts, like the 440,000-acre Levittown built between 1947 and 1951 on Long Island, N.Y. (near a Grumman aircraft factory). Forty million Americans moved to these pop-up, timber-framed suburbs in just 15 years, and then they kept moving further and further out along expanding highway systems, draining the inner city of tax revenue, jobs, and industry.