Pittsburgh – It has been called Iron City, Steel City and Smoky City, for the industrial pollution that turned its buildings and the lungs of its residents black. Today it glistens.

As we glide up the cliffs to Mount Washington on the 140-year-old Duquesne Incline, the sun sparkles on the water of the three rivers that meet directly below. It lights the two riverside stadiums - homes of the football Steelers and baseball Pirates – and the many bridges that tie the city together. Most of the bridges are painted yellow, I suspect in honor of the Steelers, Pirates and hockey Penguins, all of whom dress in black and gold.

Between the rivers is a gleaming downtown of steel and glass, two of the products that made Pittsburgh an industrial powerhouse in the 20th century. Pittsburgh’s economy was built from the minerals in the mountains around it, especially iron and coal. Mount Washington used to be named Coal Hill, for the mines once dug into the cliff overlooking downtown.

But they don’t mine coal any more on Mount Washington, where million-dollar homes now line Grandview Avenue. The local deposits of iron and coke ran out long ago. What used to be a working class neighborhood is now known for its trendy restaurants.

And they don’t make steel any more in the home of the Steelers. The air is cleaner, but the steel mills are gone, along with tens of thousands of manufacturing jobs. Its biggest employers today are hospitals, universities, insurance and financial services companies. Its action is in research, not production.

Pittsburgh is not what it used to be. Today’s Pittsburgh is young, hip, educated and green, focused on the future, not the past.

“Pittsburgh stands as a bold example of how to create new jobs and industries while transitioning to a 21st century economy, President Barack Obama said when he welcomed leaders of the G-20 nations to Pittsburgh in 2009.

Obama’s successor seems to see Pittsburgh differently, as a city he needs to protect against the future. In announcing that he was withdrawing the U.S. from the Paris Climate Accord, Donald Trump declared “I was elected to represent the citizens of Pittsburgh, not Paris.”

The mayor of Pittsburgh, Democrat Bill Peduto, disagreed. “Fact: Hillary Clinton received 80% of the vote in Pittsburgh,” he tweeted. “Pittsburgh stands with the world & will follow Paris Agreement.”

So how did Pittsburgh become the shiny buckle on America’s Rust Belt?

Pittsburgh’s long industrial history gave it some advantages. The industrial titans who made great fortunes here – including Andrew Carnegie, Andrew Mellon, George Westinghouse, and H.J. Heinz – were philanthropists as well. They endowed the kind of strong institutions, notably universities, hospitals, libraries and museums, that form the infrastructure for an innovation economy. Pittsburgh has a rich history of invention.

Pittsburgh remains a regional financial center, and is still headquarters for global corporations like U.S. Steel and PPG. Headquarters cities always fare better than branch-office locations in a down economy. The educated part of its workforce has convinced tech leaders like Amazon and Google to build campuses here.

Pittsburgh has intangibles working in its favor as well, like character, culture and pride. It regularly appears high on lists of America’s most livable cities. Don’t discount those sports teams, either. They give the city energy and identity.

Civic leadership also counts, and Pittsburgh has a history of taking its future in its hands. Shortly after World War II, a group of municipal and institutional leaders decided their city was a mess, and set about upgrading its infrastructure and cleaning its air. It put regulations on coal-burning by businesses and households. When the air was clear, they organized a campaign to get property owners to wash the grime off its downtown buildings.

There are limits to Pittsburgh’s economic success, both inside and outside the city. An innovation economy can be great for research scientists and tech entrepreneurs, but most of the workers at the city’s hospitals, universities and insurance companies aren’t making big money. Today’s jobs in retail and services don’t leave you as sick and dirty at the end of the day as yesterday’s jobs in the coal mines and steel mills, but the dirty jobs brought far bigger paychecks and better benefits.

That’s because of a factor too often omitted from our debate over lost manufacturing jobs. Most jobs in the mills weren’t intrinsically better than jobs in that have replaced them in hospitals, restaurants or offices. But they were union jobs and the unions delivered a better deal for their workers.

Pittsburgh’s prosperity also doesn’t extend far beyond the city limits. Western Pennsylvania is still hurting economically, with little hope on the horizon. And while the mayor of Pittsburgh didn’t elect Trump, his neighbors did: Trump won the five counties surrounding Pittsburgh by nearly two-to-one, a margin that by itself was enough to tip Pennsylvania to the Republicans.

Pittsburgh glistens today, but the working class prosperity that once hung like smoke over the Alleghenies is still mostly a memory.

— Rick Holmes can be reached at rick@rickholmes.net. You can follow his journey at www.rickholmes.net. Like him on Facebook at Holmes & Co, on follow him on Twitter @HolmesAndCo.