"Worrying about the decline of communities is a hallmark of modern societies and a trope among public intellectuals. Although I've written extensively about social isolation, I've long been a skeptic of claims that we're lonelier and more disconnected than we were in some mythical golden age. But even I am forced to acknowledge that, in the United States, as in other parts of the world, the social order now feels precarious. Authoritarian leaders threaten to undo entrenched democratic systems. Nations break away from political alliances. Cable news tells its viewers only what they want to hear.

"These fissures are expanding at an inopportune moment. The United States, like most developed nations, faces profound challenges — including climate change, an aging population, runaway inequality, and explosive ethnic divisions — that we can address only if we establish stronger bonds with one another and develop some shared interests too. After all, in a deeply divided society each group fends for itself above all others: The rich may make philanthropic contributions, but their own interests are paramount. The young neglect the old. Industries pollute without regard for those downwind or downstream.

"Few seem happy about these divisions — oddly, not even the winners. For much of the twentieth century, business leaders and wealthy families believed that they too would benefit from a social pact with blue-collar workers and middle-class professionals; after the Depression, they even supported housing and unemployment insurance for the poor. The system that the United States created was hardly perfect, and entire social programs (for housing, health, and education, among others) said to benefit 'the public' actually excluded African Americans and Latinos, who were forcibly relegated into separate social worlds. But by sharing the wealth, investing in vital infrastructure, and promoting an ever-expanding vision of the common good, the nation achieved unprecedented levels of not only social stability but social security too.

"Today, this collective project is in shambles. In recent decades, the 1 percent has taken home an outsize share of the nation's economic gains, while the bottom 80 percent of workers have seen their wages stagnate or decline. When millions lost their homes in the foreclosure crisis, the most affluent Americans locked up their spoils, buying 'safe deposit boxes in the sky' in soaring urban condominium towers. Those who could afford it went one step further, building survivalist retreats in New Zealand or the wooded Pacific Northwest, secluded places where they can prepare for civilization’s end. Meanwhile, the quality of public services deteriorated badly, as did the nation’s critical infrastructure. A small number of extraordinarily wealthy people built parallel private systems for air travel, personal security, even electricity; the merely well-off got fast-tracked (in airports, on special toll roads, and even in amusement park lines). The result is apparent everywhere: the great majority endures systems that are crumbling from overuse and underinvestment. Public transit lines are shoddy and overcrowded. Parks and playgrounds are poorly maintained. Public schools are underperforming. Branch libraries have reduced their hours, and in some cases closed for good. Heat, rain, fire, and wind wreak havoc on places that could once withstand them. Vulnerability is in the air.

"None of this is sustainable.

"American voters said as much in 2016, electing (albeit through the Electoral College rather than by a majority at the polls) a president who promised to blow up the system. But America’s divisions have only deepened since President Trump took office. Today, the specter of social unrest haunts cities, communities, and college campuses across the country. We fear one another, and everyone wants protection from the other side.

"As a sociologist, I have grave concerns about the powerful trembling of these social fault lines. As a citizen, I can’t help asking how we can rebuild the foundations of civil society in the kinds of diverse, democratic nations we find throughout the world today. As a student of history, I wonder how we can move beyond violent opposition to a perceived nemesis and develop a sense of shared purpose based commitments to justice and decency. As a parent of young children, I wonder whether we can repair things so that they will have a chance to flourish and not spend their lives cleaning up our mess.

"But how will we do this? Economic development is certainly one solution, though increasing national prosperity helps a society become more cohesive only if everyone — not just the most successful — shares in the gains. Besides economic growth, two ideas about how to rebuild society have dominated the conversation: One is technocratic, and involves engineering physical systems that enhance security and facilitate the circulation of people and goods. The other is civic, and involves promoting voluntary associations — the Masons, the National Association for the Advancement of Colored People, block clubs, gardening groups, and bowling leagues — that bind people into communities. Both ideas are important, but they’re only partial solutions. Social infrastructure is the missing piece of the puzzle, and building places where all kinds of people can gather is the best way to repair the fractured societies we live in today."