If I had to pick a person to illustrate why my hometown endures, even thrives, I'd pick a young engineer from India by way of California named Priya Narasimhan. She teaches at Carnegie Mellon, worships the Steelers, and, among other things, has figured out how to embed a microtransmitter in a football to electronically measure first downs.

Don't laugh: the National Football League is considering using the device.

As many people know (and the G20 leaders are about to find out), Pittsburgh has long since ceased to be a corporate center of heavy industry and manufacturing—steel, coal, oil, aluminum, glass. Instead, it's a city of universities and hospitals ("Eds and Meds"), of green technology and robotics, of financial services and yes, even entertainment, in the form of sports and world-class museums such as the Carnegie and the Warhol.

Obama's decision to host the G20 economic summit here carries with it this implicit message to the world: yes, we are borrowing lots of money from you, but if you look at Pittsburgh, you can see that we have the brains and the determination to remake ourselves in ways that will insure our long-term solvency.

In other words, China: we're still a good bet.

We will be that safe bet if the G20, which meets here starting Thursday night, can keep the world committed to the policies that attracted Narasimhan: the free flow of ideas, information, goods, and people across borders.

Global recession, Islamist terrorism, and fears about China's growing economic might combine to make nationalist barriers look attractive once again. But the saga of Pittsburgh's first rise in the 19th century—and its rebirth in the 21st—show the value of open borders. Immigrants and foreign capital built the steel industry. World markets helped it thrive. Now a new generation of immigrants—this time highly educated ones—are developing new products for new world markets.

This is where I need to promise not to get carried away with admiration for my roots. This city's wrenching transformation from brawn to brain is laudable, and instructive, but wasn't and isn't easy, clean, or complete. The city's population is half what it was when I was a kid; surrounding Allegheny County hasn't grown; nor, appreciably, has the seven-county metro area.

There are sleek new office towers downtown, but also plenty of empty storefronts on the side streets and too many frazzled and broken people waiting for the late-night bus. Four out of five kids in the city schools are on food stamps; some of the city's oldest and proudest neighborhoods—including the Hill, made famous by playwright August Wilson—are in shambles. The once-proud (and high-paying) steel industry has lost 90 percent of its work force since the days when ol' Terry Bradshaw and Mean Joe Greene roamed the playing field for the legendary Steelers of the '70s.