High Quality Content by WIKIPEDIA articles! Port Authority of Allegheny County (also known as the Port Authority or sometimes by its former nickname PAT, and formerly known as PATransit) is the second-largest public transit agency in Pennsylvania and the 11th-largest in the United States. When considering that its service area is the 20th largest in the U.S. in population, per person the Pittsburgh area enjoys more transit service than 9 larger metro areas. The county owned, state funded agency is based in Pittsburgh and is overseen by a CEO and a ten member board of directors, who report to the county executive.