Pittsburgh , Pennsylvania, located in the United States, is the second-largest city in the state and is the county seat of Allegheny County. While the city is historically known for its steel industry, today its economy is largely based on healthcare, education, technology, robotics, and financial services. The region is also becoming a hub for oil and natural gas companies' Marcellus Shale production.The city has made great strides in redeveloping abandoned industrial sites with new housing, shopping and offices, such as the Waterfront and the SouthSide Works. While Pittsburgh faced economic troubles in the mid 1980s as the steel industry waned, modern Pittsburgh is economically strong.