Pittsburgh Regional Transit is the second-largest public transit agency in Pennsylvania and the 20th-largest in the United States. The state-funded agency is based in Pittsburgh and is overseen by a CEO and a board of unpaid volunteer directors, some of whom are appointed by the county executive and approved by the county council; and one each by the majority and minority leaders by each political party. After operating as the Port Authority of Allegheny County for most of its history, the agency rebranded under its current name in June 2022. In 2023, the system had a ridership of 39,730,300.

Pittsburgh is a city in the Commonwealth of Pennsylvania and the county seat of Allegheny County. It is the second-most populous city in Pennsylvania after Philadelphia and the 68th-most populous city in the U.S., with a population of 302,971 as of the 2020 census. The city anchors the Pittsburgh metropolitan area of Western Pennsylvania. Its population of 2.457 million is the largest in both the Ohio Valley and Appalachia, the second-largest in Pennsylvania, the 7th-largest in the Mid-Atlantic region and the 26th-largest in the U.S. Pittsburgh is the principal city of the greater Pittsburgh–Weirton–Steubenville combined statistical area which includes parts of Ohio and West Virginia.