Not all that long ago, Center City's rebirth felt fragile, as though it could all turn to dust with a few ill-timed homicides or a bad economy. But Center City has proved its staying power over these last three years, thriving even as it endured trials like the flash mobs, Occupy Philly, and an atrocious real estate market, none of which is exactly the stuff of idealized urban living.
Center City rode over those speed bumps with ease, its momentum barely slowed. That suggests to me it has passed a tipping point: It's no longer a delicate flower, and there's a certain sense of inevitability to its continued expansion.
Let's acknowledge that celebrating an increase in the city's white population is a bit crass. But the consequences of white flight (and, increasingly, middle-class black flight) have been so disastrous for so many cities for so long that this reversal - however slight - is momentous.
Not because of race per se, but because of affluence. The white residents swelling Center City tend to be reasonably well-off and highly educated. That means they pay a lot in taxes while requiring relatively little in the way of city services, a combination that makes them a welcome addition to the poorest big city in the country.
Of course, there are some drawbacks to their increase in Philadelphia. Gentrification tensions are common along many of Center City's bleeding edges. And one wonders what will happen to Philadelphia's very identity - so closely linked to the city's white ethnic neighborhoods - once the white population is dominated not by Joey and Stacey from the block, but by Jacob and Sophia from Swarthmore.
We could find out sooner than you might imagine.
In his new book, The Great Inversion and the Future of the American City, urbanist Alan Ehrenhalt argues that "we are living at a moment in which the massive outward migration of the affluent that characterized the second half of the 20th century is coming to an end."
In other words, rich white people are moving to city centers not just in Philadelphia, but also in Atlanta, Chicago, Phoenix, and plenty of other cities.
But as Ehrenhalt's chapter on Philadelphia ("Uneasy Coexistence") convincingly shows, it takes more than a few - or even a bunch of - rich white people moving downtown to save a city.
Philadelphia's core, he writes, "is a fashionable center surrounded on two of its four sides by a periphery of seemingly endless poverty."
Philadelphia, he says, occupies a strange space between Chicago and Boston on the one hand, and Detroit on the other: a city both glamorous and exciting, and so blighted and dangerous many would shun it.
And for every good demographic indicator (such as the reversal or ebbing of white flight), another is deeply troubling (such as the sharp decline in the city's African American middle class).
In Ehrenhalt's view, Philadelphia's liabilities - namely the blight, violence, and taxes - are so extreme they will ultimately put a halt to Center City's growth. In other words, instead of the engine that powers the redevelopment of all of Philadelphia, Center City is more likely to stay an affluent island amid mass poverty.
And maybe so. But an island is better than nothing, and Center City isn't done expanding yet.
Patrick Kerkstra is a freelance journalist and former Inquirer staff writer. Follow him on Twitter @pkerkstra.