Allegheny County, PA
Located in the southwestern part of Pennsylvania, Allegheny County encompasses 745 mi². Population records report 1,218,452 as 2018, making Allegheny County the second most populous in the state of Pennsylvania. Allegheny was established on September 24, 1788, and the county seat is situated in its largest city, Pittsburgh. The climate is temperate, averaging 38 inches of rain and 28 inches of snow a year. Top five leading industries in the county are advanced manufacturing, healthcare, energy, financial and business services, and information technology.