Answer:
As the cold war was starting, America began to protect major cities. One of them was Pittsburgh. One of the reasons it was protected was because it was an industrial city which was big in the production of steel.
When steel industries began to wane and so did the blue-collar jobs.
Pittsburgh, however, by the middle of the twentieth century repositioned its the economy to have large medical providers, numerous colleges, universities, including research and development leaders. It also became the home to a lot of the tech companies that we have today. This move was intentional and helped the economy thrive even during the recession of the late 20th century.
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