The Strange Decline of the Philly Accent

Sometime around the 1960s and '70s, people in Philadelphia began slowly, subtly to change how they speak. The sound of their vowels started a gradual shift consciously imperceptible to the very people who were driving it. A's evolved to bump into E's. The sound of an O lost some of its singsong twang. After decades of speaking with what was in effect a southern dialect, Philadelphians were becoming – linguistically, that is – more northern.

"There's one big question: How is it possible that Philadelphians all over the city are doing the same thing?" asks Bill Labov, a professor in the department of linguistics at the University of Pennsylvania. "What is it that makes Philadelphia operate as a whole, making it different from the neighboring cities?"