Allegheny County, PA

Allegheny County, Pennsylvania
Allegheny County Courthouse
Flag Seal
Location in the U.S. state of Pennsylvania
Pennsylvania's location in the U.S.
Founded	September 24, 1788
Named for	Allegheny River
Seat	Pittsburgh
Largest city	Pittsburgh
Area
• Total	745 sq mi (1,930 km2)
• Land	730 sq mi (1,891 km2)
• Water	14 sq mi (36 km2), 1.9%
Population (est.)
• (2016)	1,225,365
• Density	1,686/sq mi (651/km²)
Congressional districts	12th, 14th, 18th
Time zone	Eastern
Website	www.alleghenycounty.us
Footnotes:
Pennsylvania Historical Marker
Designated	December 30, 1982

Allegheny County (/ælɪˈɡeɪni/) is a county in the southwest of the U.S. state of Pennsylvania. As of 2016 the population was 1,225,365, making it the state's second-most populous county, following Philadelphia County. The county seat is Pittsburgh. Allegheny County is included in the Pittsburgh, PA Metropolitan Statistical Area, and in the Pittsburgh Designated Market Area.

Allegheny was Pennsylvania's first to bear a Native American name, being named after the Allegheny River. The word "Allegheny" is of Lenape origin, with uncertain meaning. It is usually said to mean "fine river", but sometimes said to refer to an ancient mythical tribe called "Allegewi" that lived along the river before being destroyed by the Lenape.

Little is known of the region's inhabitants prior to European contact. During the colonial era, various native groups claimed or settled in the area, resulting in a multi-ethnic mix that included Iroquois, Lenape, Shawnee, and Mingo. European fur traders such as Peter Chartier established trading posts in the region in the early eighteenth century.

In 1749, Captain Pierre Joseph Céloron de Blainville claimed the Ohio Valley and all of western Pennsylvania for Louis XV of France. The captain traveled along the Ohio and Allegheny rivers inserting lead plates in the ground to mark the land for France.