In his 1987 book, “Bourgeois Utopias,” the historian Robert Fishman pointed out that “suburbia was at once the most characteristic product of explosive urban expansion and a desperate protest against it.” Many policymakers and homeowners are, in effect, still living within that tension, in denial of the ways the modern suburb already reflects trends in domestic arrangements away from the traditional conception of family and toward a lifestyle and experience that feels distinctly metropolitan. In recent years, it has almost became a cliché for real estate agents to describe commuter towns outside New York as “Brooklynish,” even though the great virtue of Brooklyn is that nearly 2.6 million people live there, roughly half of them foreign-born, in apartment buildings.

Despite the pretenses we maintain, Mr. Fishman argued, suburbia is not static. Rapid growth in the 1940s and ’50s fed the myth that suburbanization was an invention of the postwar period, when it had been part of the American landscape since the late 19th century. Unlike the Levittowns of 1957, these early suburbs were not as homogeneous, because the wealthy people who lived there were so reliant on domestic labor. In the absence of efficient mass transit, the difficulty of getting to these places from big cities meant that a certain amount of work force housing had to be nearby.

Over the past several decades, the phobia around density has run deep, whether a particular community is distinguished by its liberal affluence, barre studios and Alsatian restaurants or by a middle-class law-and-order conservatism. In a survey conducted last year, 63 percent of those living in suburbs said that they believed density increased traffic congestion even though the opposite is often true, given that greater density is typically accompanied by larger investments in public transportation.

The more vaporous claim that density threatens a certain “way of life” requires us to ask: What way? In 1960, during the high period of the ranch house, 44 percent of American households were made up of married couples with children. By 2020, that figure had dropped to 19 percent. During the same period, the proportion of households containing only a single individual more than doubled, to 28 percent. We treat the single-family house as sacrosanct perhaps out of a desperation to ignore that the primacy of the single family has itself receded.

Across the country, suburbs have become much less racially and ethnically monolithic. In 2010, the population of Nassau County was 66 percent white; now it is 57 percent white. There are vibrant Hispanic, South Asian, Chinese and Korean communities.