Allegheny County, Pennsylvania

Allegheny County
Allegheny County Courthouse
Flag of Allegheny County
Official seal of Allegheny County
Official logo of Allegheny County
Map of Pennsylvania highlighting Allegheny County
Location within the U.S. state of Pennsylvania
Map of the United States highlighting Pennsylvania
Pennsylvania's location within the U.S.
Coordinates: 40°26′08″N 80°01′28″W / 40.4356°N 80.0244°W / 40.4356; -80.0244
Country United States
State Pennsylvania
FoundedSeptember 24, 1788
Named forAllegheny River
SeatPittsburgh
Largest cityPittsburgh
Area
 • Total745 sq mi (1,930 km2)
 • Land730 sq mi (1,900 km2)
 • Water14 sq mi (40 km2)  1.9%
Population
 (2020)
 • Total1,250,578
 • Estimate 
(2023)
1,224,825 Decrease
 • Density1,700/sq mi (700/km2)
Time zoneUTC−5 (Eastern)
 • Summer (DST)UTC−4 (EDT)
Congressional districts12th, 17th
Websitealleghenycounty.us
DesignatedDecember 30, 1982[1]
Map
Interactive map of Allegheny County, Pennsylvania

Allegheny County (/ˌælɪˈɡni/ AL-ig-AY-nee) is a county in Pennsylvania, United States. As of the 2020 census, the population was 1,250,578, making it the state's second-most populous county, after Philadelphia County. Its county seat and most populous city is Pittsburgh, Pennsylvania's second most populous city.[2] The county is part of the Greater Pittsburgh region of the commonwealth,[a] and is the center of the Pittsburgh media market.

Allegheny was the first county in Pennsylvania to be given a Native American name. It was named after the Lenape word for the Allegheny River. The meaning of "Allegheny" is uncertain. It is usually said to mean "fine river". Some historians state that the name may come from a Lenape account of an ancient mythical tribe called "Allegewi", who lived along the river before being taken over by the Lenape.[3]

  1. ^ "PHMC Historical Markers Search". Pennsylvania Historical and Museum Commission. Commonwealth of Pennsylvania. Archived from the original (Searchable database) on March 21, 2016. Retrieved January 25, 2014.
  2. ^ "Find a County". National Association of Counties. Archived from the original on May 31, 2011. Retrieved June 7, 2011.
  3. ^ Stewart, George R. (1967) [1945]. Names on the Land: A Historical Account of Place-Naming in the United States (Sentry edition (3rd) ed.). Houghton Mifflin. pp. 8, 193. ISBN 1-59017-273-6.


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