PHILADELPHIA — Cheesesteaks? Never mind. Sichuan shoestring French fries? That’s more like it. Like many American cities, Philadelphia has greatly evolved both economically and culturally since 2000, the last time a major political party held its national convention here, not to mention the days when W. C. Fields made it a national punch line.

While its public school system remains a mess, its crime rate elastic and its poverty rate high, Philadelphia has been revitalized over the last decade and a half, with celebrity chefs, a vibrant technology sector and thriving art scene, all boxes to check for cities on the move these days.

“Yes, the schools are still a problem, crime is still a problem, gun violence is still a problem,” said Senator Bob Casey, a Pennsylvania Democrat who has watched Philadelphia evolve over several decades. “But people have much more optimism about the future now. With the pope coming in 2015 and the Democrats in 2016, it’s a one-two punch.”

The story of Philadelphia, which the Democrats chose on Thursday as the venue for their national convention in 2016, is less a tale of two cities than a nuanced novel with overlapping plots.