In the mid-1980s, when I was on my high school’s cross-country team, I used to run along Penn Avenue from my hometown, Wilkinsburg, into the East Liberty neighborhood of Pittsburgh. I never knew exactly during those days where I entered or exited either city.

Buttressed by the nearby Westinghouse Electric complex, Wilkinsburg’s downtown flowed into East Liberty. Wilkinsburg was mixed, about 53 percent black, and the black residents of Wilkinsburg, including my adoptive parents, worked and went to school in both places. You could easily miss the changing color of the street signs from green (Wilkinsburg) to blue (Pittsburgh). The smell from the Nabisco factory, just across the border on the Pittsburgh side, was a better signal. The buttery smell of Ritz crackers welcomed me into the bigger city.

The 1990s were especially hard on both Wilkinsburg and East Liberty. Westinghouse laid off thousands of workers. The Nabisco factory closed in 1998. With fewer jobs available, dozens of my classmates sold drugs, ending up addicted, in jail or dead from related violence. I was lucky; I left for college and made a career for myself in other cities.

Over the past decade or so, things started to change in Pittsburgh, but only one of those areas benefited. By 2010, Pittsburgh had reinvented itself as a tech hub — it is one of 20 finalists to land Amazon’s second headquarters — and that new identity is anchored by Google’s engineering office in East Liberty. What used to be the site of the Nabisco factory is now called Bakery Square, a mixed-use development with apartments, fancy retail shops, a gym, chic restaurants and bars, and bike trails to Mellon Park, where Google engineers and others who have flocked to the neighborhood enjoy walking paths, and basketball and tennis courts. Until recently, driverless cars roamed the streets.