Sentence:  The big factories which are relatively near the centers of our cities - the rubber factories in Akron , Chrysler 's Detroit plants , U. S. Steel 's <WSD>Pittsburgh</WSD> works - often began on these sites at a time when that was the edge of the city , yet close to transport ( river ) , storage ( piers ) and power ( river ) . 
Meaning of the word marked with <WSD> tags:  a city in southwestern Pennsylvania where the confluence of the Allegheny River and Monongahela River forms the Ohio River; long an important urban industrial area; site of Carnegie Mellon University and the University of Pittsburgh