Pittsburgh is a city in the state of Pennsylvania in the United States, and is the county seat of Allegheny County. An estimated population of about 300,286 residents live within the city limits as of 2019, making it the 66th-largest city in the U.S. and the second-most populous city in Pennsylvania, behind Philadelphia. The Pittsburgh metropolitan area is the anchor of Western Pennsylvania; its population of 2.32 million is the largest in both the Ohio Valley and Appalachia, the second-largest in Pennsylvania, and the 27th-largest in the U.S. Pittsburgh is located in the southwest of the state, at the confluence of the Allegheny River and the Monongahela River, forming the Ohio River. Pittsburgh is known both as “the Steel City” for its more than 300 steel-related businesses and as the “City of Bridges” for its 446 bridges. The flag of Pittsburgh, Pennsylvania is a triband flag featuring vertical bands of black and gold and the city’s coat of arms in the center. Full HD.