Much is being written right now about the years 1968 and 2020, seeking to compare the urban disorder of Richard Nixon's election year with the disorder that is taking place in the middle of Donald Trump's campaign for re-election. I think it's a useful comparison, but I'd like to try it a different way. I want to ponder what living in a large American city was like 50 years ago and what it is like in the 21st century.

When I think of the Chicago of my youth in the 1960s, I sometimes find myself thinking of Archie Bunker. It's an odd notion in many ways: Archie never lived in Chicago, and the TV series that made him famous didn't even appear until 1971. Still, all American cities in the late 1960s were teeming with people like Archie Bunker: middle-aged working-class white men of limited education, many of them children of immigrants, employed in tedious but secure blue-collar jobs in factories or on loading docks or at city patronage enclaves, and living in brick bungalows with large families, crowded but one happy step up from the tenements of the pre-war years. These people were the core of '60s and '70s urban life. As Nicholas Lemann put it succinctly in his recent book, Transaction Man, there were three icons of this life: the Democratic Party, the Catholic Church and the employers the workers felt committed to for life.

Nearly all of them spouted off prejudices that they didn't bother to disguise at all. "They're wonderful people," Archie said of the Black people that he knew. "But they are also colored people. … If God had meant for us to be together he'd a put us together."

In Chicago, the one thing these working-class families feared most was that Blacks would sweep into their neighborhoods, pressure them to sell their modest homes at fire-sale prices, sit next to their children in public schools, and raise the specter of violent conflict on neighborhood streets. I'm not saying these were rational fears; I'm just reporting the things that blue-collar Chicago believed. And Chicago was a blue-collar city. So were virtually all American cities. We sometimes forget that.

Richard J. Daley was the mayor and political boss of Chicago, a man whom history has in part misunderstood. Daley regarded himself as a friend and patron of Black people, and when he ran for re-election in 1963 he actually lost the white vote because he was perceived as too close to Blacks. It was the African American wards that saved Daley that year. Only after his 1963 electoral scare did Daley make the conspicuous rightward moves that culminated in his incendiary rhetoric during the riots after the death of the Rev. Martin Luther King Jr. in 1968.

WHILE CHICAGO'S WHITE BUNGALOW BELT was enduring a stressful decade, the African American neighborhoods that lay east of it were experiencing long-sought but destabilizing change. The tight segregation that had packed them into a relatively small portion of the city was slowly breaking up, and Black middle-class residents were moving into areas that had been categorically closed to them in the past.

But as many of them recognized, the coming of even modest desegregation brought the erosion of the vibrant Black community life that had characterized Bronzeville and other South Side neighborhoods for the previous half-century. Black-owned banks, insurance companies, funeral parlors, small department stores and, most crucially, the neighborhood Baptist churches were closing or losing their vitality. As the long-trapped Black middle class began to spread out across the city, Bronzeville and its counterpart communities were left with an underemployed, frequently rootless housing-project cohort for which desegregation had meant alienation rather than liberty.

If you were growing up white on the South Side, as I was, you knew that the police were frequently crooked in dealing with both races. They took on-the-scene bribes as a way of shaking down minor traffic offenders; they colluded with towing companies that paid them for the privilege of taking cars off the street and bilking the owners who had to get them back. In the late 1950s, police officers actually had been part of a burglary ring. In a public elementary school, you could pick out the natural bullies and assume that a fair number of them would join the police force.

But for the middle-class youth of Chicago and all other cities, the overwhelming life concern wasn't crime and it wasn't corruption: It was Vietnam. Virtually no one wanted to go; virtually everyone feared being drafted. This was a worry that was never far from everyday existence. What few of us understood at the time was that, in the end, we wouldn't be the primary victims of the brutal Asian war — it would be disproportionately the sons of the Archie Bunkers in the Bungalow Belt and the minorities farther east. The families of these boys did understand what was going on, that few college kids would be paying the ultimate price, and this was part of their wide-ranging resentment, although most of them continued to support the war itself.

One must grasp the mentality of blue-collar urbanites in these years to understand some of the things that politicians were saying at the time, and to understand how the politicians got away with them. In 1968, Mayor Daley ordered police to "shoot to kill arsonists" and "shoot to maim looters." But this was not the worst. Alabama Gov. George Wallace, running for president, warned that if a protester lay down in front of his car it would be the last one he ever lay down in front of. In other words, he was advocating murder. Delaware Gov. Charles Terry, panicked by rioting in his state, implanted National Guard troops on the streets of Wilmington and kept them there for eight months, long after any possible threat had disappeared. A while later, Frank Rizzo, the mayor of Philadelphia, promised to "make Attila the Hun look like a faggot."

Horrific as the recent episodes of police violence have been, no elected city leader would even think of taking any of those actions today, in part because national sensibilities have changed but also because of the drastically altered makeup of urban America.

SOME OF THE CHANGES IN CHICAGO are fairly obvious; some are not. But the difference most often overlooked is the virtual absence of the blue-collar population that gave the city its essential character 50 years ago. There are only a few white working-class neighborhoods left anywhere in Chicago; many of the people who live in them are city employees. The Archie Bunkers of 1968 have mostly passed away; their children are exurbanites, in two senses of that word: They have moved not only because of racist fears but because the blue-collar jobs they held have left the city as well.

What this means is that America's large cities have become enclaves of affluent, liberal, well-educated professionals and much less affluent minorities. Journalists and academics like to point out that a number of big cities have been losing population in the last few years, and this is true, but it misses a crucial point: Many of these cities have been growing more affluent even as they have been losing people. Chicago lost more than 200,000 people in the first decade of this century, but much of the city was growing wealthier at the same time. The wealth was concentrated in the central city and in the surrounding neighborhoods. A recent Brookings study documented how big-city downtowns nearly all continued to gain population even as their cities contracted slightly in the recession years that followed the 2008 economic collapse.

When cities lost their working-class flavor, they lost their family flavor as well. Gentrified Chicago is a city of singles and couples holding jobs in the professional economy. Most of the couples have no children, or leave the city with their one- or two-child families when the kids move into the middle years of school. Critics have argued that the dearth of families means that places such as Chicago aren't even cities in the traditional sense. This may be true, but it seems more useful to say that they are cities in a new way that needs to be understood rather than denigrated.

Crime is a concern in the gentrified city, but almost entirely in the poorest minority neighborhoods. That is where virtually all the murders and other violent crimes take place. In the professional enclaves, there is little crime and little racial tension. For the most part, white and African American professionals get along with each other well.

All of this helps to explain why city residents have reacted as they have toward the racial disturbances and complaints of police brutality that have characterized the spring of 2020, and also why the politicians who govern these cities have made the choices they have made.

Elected city officials can no longer react to disturbances in the manner of Daley and Rizzo because there is no urban blue-collar constituency that would countenance such backlash rhetoric. Moreover, mayors like that couldn't be elected in the first place. Politicians with white working-class roots do run some city halls these days, such as Martin Walsh in Boston and Jim Kenney in Philadelphia, but only if they have moved to the progressive side of the fence. When racially tinged violence occurs, they respond to the interests and values of the professionals and minorities who now comprise most of the city. Backlash sentiments exist in this country, but they are concentrated, somewhat ironically, in the rural areas and small towns far from where the disturbances actually occur.

Values matter in politics, and the values of the nation have evolved in the years since 1968, but when it comes to big cities, demographic change matters more. To understand a city, it's important to know what its residents think. But it's even more important to know who the residents are.