Pittsburgh is a city in the Commonwealth of Pennsylvania in the United States, and is the county seat of Allegheny County. As of 2017, a total population of 305,704 inhabitants within the city limits. The metropolitan population of 2,353,045 is the largest in both the Ohio Valley and Appalachia, and the second-largest in Pennsylvania (behind Philadelphia).
The area is home to 68 colleges and universities, including research and development leaders Carnegie Mellon University and the University of Pittsburgh.
Pittsburgh is known as both "the Steel City" for its more than 300 steel-related businesses, and as the "City of Bridges" for its 446 bridges. Aside from steel, Pittsburgh has led in manufacturing of aluminum, glass, shipbuilding, petroleum, foods, sports, transportation, computing, autos, and electronics. After the collapse of its century-long steel and electronics industries. The region has shifted to high technology, robotics, health care, nuclear engineering, tourism, biomedical technology, finance, education, and services. Reflecting the citywide shift from industry to technology, former factories have been renovated as modern office space.
Today the region is a hub for Leadership in Energy and Environmental Design, sustainable energy, and energy extraction.
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