My barber voted for Lori Lightfoot, and she's excited to see her take office. But I’m worried she may be expecting something from Lightfoot that no mayor can deliver.

“I hope she does something about gentrification,” she said. “I had to move from Logan Square to Avondale because it got too expensive. Why should I have to move? I’ve lived there all my life.”

Never mind that Lightfoot lives in Logan Square herself, buying a 19th Century A-frame there in 2004. In the United States, there’s not much a public official — especially a mayor — can do to influence free market outcomes. Increasingly, the wealthy want to live in the city, especially downtown and on the Northwest Side. And wherever wealthy people go, they attract even more wealthy people.

In her inauguration speech, delivered Monday at Wintrust Arena, Lightfoot vowed to make Chicago “a city that is affordable for families and seniors and where every job pays a living wage. A city of fairness and hope and prosperity for the many, not just for the few, a city that holds equity and inclusion as our guiding principles.”

I’m sure Lightfoot is sincere in that goal. But the fact is, Chicago, which used to be known as “the promised land” for the economic enrichment it represented to immigrants and black Americans fleeing the Jim Crow South, is no longer a blue-collar, bootstrap city. It’s become a city bifurcated between haves and have-nots, for reasons that have less to do with decisions made in City Hall than they do the global economy.

Chicago’s inequality is the result of the same forces that have made the gap between rich and poor in America wider than at any time since the 1920s: globalization, the shift from a manufacturing to a tech economy, and the loss of union jobs. The gentrification of the Loop and the Northwest Side is a result of what urbanist Alan Ehrenhalt calls The Great Inversion: “the center of the city is going to be where affluent people choose to live, [and] suburbs are going to be the place where immigrants and the poor congregate," he said in a 2012 interview.

On the day of Lightfoot’s inauguration, South Shore native Carlo Rotella published an editorial about his old neighborhood in The New York Times, titled “A Shrinking Middle Class is Ruining the Character of Our Neighborhoods.” It’s based on his new book, The World Is Always Coming to an End: Pulling Together and Apart in a Chicago Neighborhood.

When Rotella was growing up in the 1970s, South Shore was “a first-house neighborhood where police officers, nurses, bus drivers, postal workers, small-business owners and unionized city workers and factory workers climbed up into the middle class and tried to put their kids in position to aim still higher.”

Today, the neighborhood is divided between a majority of low-income renters and a small group of well-off professionals who sequester themselves behind iron gates and security cameras.

“If you want to see what our cities are going to be like when we’re done reversing the great postwar expansion of the middle class, neighborhoods like South Shore are a good place to look,” writes Rotella. “[Y]ou can detect the tectonic grinding of vast economic and social forces at work beneath the surface of the neighborhood.”

Lori Lightfoot cannot restore the great postwar expansion of the middle class, not from the 5th Floor of City Hall. Not even a president can do that. The middle class continues to shrink with every administration.

The difference between Lightfoot and her predecessor, though, is that she gives a damn that the middle class is shrinking, and she wants to enact policies that will cushion the fall for people tumbling out of it. Rahm Emanuel may be a Democrat, but he’s the closest thing you’ll find in that party to a Wall Street Journal editorial page free-market absolutist.

Emanuel didn’t set out to perform an economic cleansing of Chicago, but he didn’t do much to stop it, either. He rode the wave of Chicago’s transformation into a city of highly educated professionals. He brought Google to the West Loop and made sure its employees had comfortable places to live, work, and play, spending $95 million on the Riverwalk he hopes will someday bear his name.

At the same time, Emanuel closed six mental health clinics, most of them in low-income neighborhoods. Lightfoot promised to “repair our broken mental health safety net.” Emanuel raised water rates. Lightfoot is ending water shut-offs, calling them "heartless."

Lightfoot also wants to build more affordable housing — and end the practice of aldermanic prerogative that allows aldermen to keep it out of their wards.

“Stability also means that we must build housing that is affordable for more people, including families,” Lightfoot said in her speech. “Long term residents — whether homeowners or renters — should not be forced out of their neighborhoods when it goes through a period of transformation. And developers can no longer skip their responsibilities by taking tax dollars but leaving it to someone else to solve our affordable housing crisis.”

With Lightfoot as mayor, will gentrification continue to spread south from the Loop and northwest from Logan Square? Yes, it will. Will the black population continue to shrink, while the city attracts more young professionals from out of state? That will probably keep happening, too. Will luxury apartment towers continue rising in the Loop, while two-flats are demolished in West Garfield Park? You bet.

Lightfoot can’t reverse any of that. What she can do is try to make life a little less hard for Chicagoans on the wrong side of those trends. In her inaugural address, she announced her intention to do that.