Scranton is the sixth-largest city in the Commonwealth of Pennsylvania behind Philadelphia, Pittsburgh, Allentown, Erie and Reading. It is the county seat of Lackawanna County in Northeastern Pennsylvania's Wyoming Valley and hosts a federal court building. With a population of 77,291, it is the largest city in the Scranton–Wilkes-Barre–Hazleton, PA Metropolitan Statistical Area, which has a population of about 570,000.Scranton is the geographic and cultural center of the Lackawanna River valley, and the largest of the former anthracite coal mining communities in a contiguous quilt-work that also includes Wilkes-Barre, Pittston, and Carbondale. Scranton was incorporated on February 14, 1856, as a borough in Luzerne County and as a city on April 23, 1866. It became a major industrial city, a center of mining and railroads, and attracted thousands of new immigrants. It was the site of the Scranton General Strike in 1877.