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Allegheny County, Pennsylvania facts for kids

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Allegheny County
Allegheny County Courthouse
Flag of Allegheny County
Official seal 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.
Country  United States
State  Pennsylvania
Founded September 24, 1788
Named for Allegheny River
Seat Pittsburgh
Largest city Pittsburgh
 • Total 745 sq mi (1,930 km2)
 • Land 730 sq mi (1,900 km2)
 • Water 14 sq mi (40 km2)  1.9%%
 • Total 1,250,578
 • Density 1,713/sq mi (661/km2)
Time zone UTC−5 (Eastern)
 • Summer (DST) UTC−4 (EDT)
Congressional districts 17th, 18th
Pennsylvania Historical Marker
Designated: December 30, 1982

Allegheny County is located in the southwest of the U.S. state of Pennsylvania. As of the 2020 census, the population was 1,250,578, 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 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". Stewart says 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.


Not a great deal is known about the native inhabitants of the region 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.

Since most of the towns during that era were developed along waterways, both the French and the British desired control over the local rivers. Therefore, the British sent Major George Washington to try to compel the French to leave their posts, with no success. Having failed in his mission, he returned and nearly drowned crossing the ice-filled Allegheny River. In 1754, the English tried again to enter the area. This time, they sent 41 Virginians to build Fort Prince George. The French got news of the plan and sent an army to take over the fort, which they then resumed building with increased fortification, renaming it Fort Duquesne.

The loss of the fort cost the English dearly because Fort Duquesne became one of the focal points of the French and Indian War. The first attempt to retake the fort, the Braddock Expedition, failed miserably. It was not until General John Forbes attacked in 1758, four years after they had lost the original fort, that they recaptured and destroyed it. They subsequently built a new fort on the site, including a moat, and named it Fort Pitt. The site is now Pittsburgh's Point State Park.

Both Pennsylvania and Virginia claimed the region that is now Allegheny County. Pennsylvania administered most of the region as part of its Westmoreland County. Virginia considered everything south of the Ohio River and east of the Allegheny River to be part of its Yohogania County and governed it from Fort Dunmore. In addition, parts of the county were located in the proposed British colony of Vandalia and the proposed U.S. state of Westsylvania. The overlapping boundaries, multiple governments, and confused deed claims soon proved unworkable. In 1780 Pennsylvania and Virginia agreed to extend the Mason–Dixon line westward, and the region became part of Pennsylvania. From 1781 until 1788, much of what had been claimed as part of Yohogania County, Virginia, was administered as a part of the newly created Washington County, Pennsylvania.

Allegheny County was officially created on September 24, 1788, from parts of Washington and Westmoreland counties. It was formed due to pressure from settlers living in the area around Pittsburgh, which became the county seat in 1791. The county originally extended all the way north to the shores of Lake Erie and became the "mother county" for most of what is now northwestern Pennsylvania. By 1800, the county's current borders were set.

In the 1790s, a whiskey excise tax was imposed by the United States federal government. This started the so-called Whiskey Rebellion when the farmers who depended on whiskey income refused to pay and drove off tax collector John Neville. After a series of demonstrations by farmers, President George Washington sent troops to stop the rebellion.

The area developed rapidly throughout the 19th century to become the center of steel production in the nation. Pittsburgh would later be labeled the "Steel Capital of the World".


According to the U.S. Census Bureau, the county has a total area of 745 square miles (1,930 km2), of which 730 square miles (1,900 km2) is land and 14 square miles (36 km2) (1.9%) is water.

Allegheny County is known for the three major rivers that flow through it: the Allegheny River and the Monongahela River converge at Downtown Pittsburgh to form the Ohio River. The Youghiogheny River flows into the Monongahela River at McKeesport, 10 miles (16 km) southeast. Several islands are located within the riverine systems. Water from these rivers eventually flows into the Gulf of Mexico via the Mississippi River. Although the county's industrial growth caused the clearcutting of forests, a significant woodland remains.

Adjacent counties

Major Highways

  • I-76 / Penna Turnpike
  • I-79
  • I-279
  • I-376
  • I‑376 Bus.
  • I-579
  • US 19

  • US 19 Truck

  • US 19 Byp.
  • US 22

  • US 22 Bus.
  • US 30

  • US 30 Truck
  • PA 8
  • PA 28
  • PA 51
  • PA 65
  • PA 130
  • PA 380
  • Toll PA 576
  • PA 837


Historical population
Census Pop.
1790 10,203
1800 15,087 47.9%
1810 25,317 67.8%
1820 34,921 37.9%
1830 50,552 44.8%
1840 81,235 60.7%
1850 138,290 70.2%
1860 178,831 29.3%
1870 262,204 46.6%
1880 355,869 35.7%
1890 551,959 55.1%
1900 775,058 40.4%
1910 1,018,463 31.4%
1920 1,185,808 16.4%
1930 1,374,410 15.9%
1940 1,411,539 2.7%
1950 1,515,237 7.3%
1960 1,628,587 7.5%
1970 1,605,016 −1.4%
1980 1,450,085 −9.7%
1990 1,336,449 −7.8%
2000 1,281,666 −4.1%
2010 1,223,348 −4.6%
2020 1,250,578 2.2%
U.S. Decennial Census
1790–1960 1900–1990
1990–2000 2010–2018

As of the 2010 census, there were 1,223,348 people living in the county. The population density was 1676 people per square mile (647/km2). The racial makeup of the county was 82.87% White, 14.39% Black or African American, 2.94% Asian, 0.03% Pacific Islander, 0.37% from other races, and 1.40% from two or more races. About 1.31% of the population were Hispanic or Latino of any race.

At the census of 2000, there were 1,281,666 people, 537,150 households, and 332,495 families living in the county. The population density was 1,755 people per square mile (678/km2). There were 583,646 housing units at an average density of 799 per square mile (309/km2). The racial makeup of the county was 84.33% White, 12.41% Black or African American, 0.12% Native American, 1.69% Asian, 0.03% Pacific Islander, 0.34% from other races, and 1.07% from two or more races. About 0.87% of the population were Hispanic or Latino of any race. 20.0% were of German, 15.0% Italian, 12.7% Irish, 7.5% Polish and 5.1% English ancestry according to Census 2000. 93.5% spoke English and 1.3% Spanish as their first language.

There were 537,150 households, out of which 26.40% had children under the age of 18 living with them, 46.10% were married couples living together, 12.40% had a female householder with no husband present, and 38.10% were non-families. Some 32.70% of all households were made up of individuals, and 13.20% had someone living alone who was 65 years of age or older. The average household size was 2.31 and the average family size was 2.96.

The age distribution of the population shows 21.90% under the age of 18, 8.50% from 18 to 24, 28.30% from 25 to 44, 23.40% from 45 to 64, and 17.80% who were 65 years of age or older. The median age was 40. For every 100 females, there were 90.00 males; for every 100 females age 18 and over, there were 86.20 males.



Allegheny County's public transportation provider is the Port Authority of Allegheny County. The Allegheny County Department of Public Works oversees infrastructure, maintenance, and engineering services in the county.

The Three Rivers Heritage Trail provides uninterrupted bicycle and pedestrian connections along the three rivers in the city, and the Great Allegheny Passage trail runs from downtown Pittsburgh to Washington, D.C.

The Allegheny County Airport is the original airport for Pittsburgh and houses a number of flight schools, charter flight operations, and medevac operations.

Major roadways

  • Interstate 79 runs north to south from Warrendale to Bridgeville
  • Interstate 279 runs north to south from Franklin Park to Downtown
  • Interstate 579 (Crosstown Boulevard), from Interstate 279 on the north shore to Liberty Bridge / Boulevard of the Allies
  • Interstate 76 / PA Turnpike runs east to west from Interstate 376 in Monroeville to the Warrendale interchange (at Interstate 79)
  • Interstate 376 runs east to west from Interstate 76 in Monroeville across the county to Pittsburgh International Airport and beyond
  • Pennsylvania Turnpike 576 (future I-576) runs south from Interstate 376 at the Pittsburgh International Airport to US Route 22, also called the Findlay Connector. The next phase of this road extension, from US Route 22 to Interstate 79 running along the County line, is currently under construction and is expected to be open to traffic in 2020.
  • US Route 19 runs north to south from Warrendale to Upper St. Clair
  • US Route 22 runs west to east, along much of US Route 30 and Interstate 376, from Imperial to Monroeville
  • US Route 30 runs west to east from Clinton to North Versailles, joining US 22 and Interstate 376 south of the Pittsburgh International Airport and leaving those same two routes in Wilkinsburg

For information about major state roads, see list of State Routes in Allegheny County, Pennsylvania and Allegheny County Belt System.

Parks and recreation

There are two Pennsylvania state parks in Allegheny County. Point State Park is at the confluence of the Allegheny and Monongahela rivers in Downtown Pittsburgh, and Allegheny Islands State Park is in the Allegheny River in Harmar Township and is undeveloped as of August 2010.


Map of Allegheny County Pennsylvania With Municipal and Township Labels
Map of Allegheny County, Pennsylvania, with municipal labels showing cities and boroughs (red), townships (white), and census-designated places (blue)

Under Pennsylvania law, there are four types of incorporated municipalities: cities, boroughs, townships, and (in one case) a town. The following municipalities are in Allegheny County:




Census-designated places

Census-designated places are geographical areas designated by the US Census Bureau for the purposes of compiling demographic data. They are not actual jurisdictions under Pennsylvania law. Other unincorporated communities, such as villages, may be listed here as well.

Unincorporated communities

Former places

Many political subdivisions of Allegheny County have come and gone through subdivision or annexation through the years. These include:

  • Allegheny City – the area that is now the North Shore (or North Side) of the City of Pittsburgh, north of the Allegheny River.
  • Allentown Borough – now the neighborhood of Allentown in Pittsburgh.
  • Birmingham Borough – what is now Pittsburgh's South Side.
  • Brushton Borough
  • Carrick Borough – now the neighborhood of Carrick. Formed out of Baldwin Township in 1904, this borough existed until it was annexed by Pittsburgh in 1927. It was named for Carrick-on-Suir, Ireland. To this day, some of the manhole covers bear the Carrick Borough name.
  • Collins Township – in what is now the northeast part of the City of Pittsburgh, east of Lawrenceville and north of Penn Avenue.
  • Knoxville Borough
  • Lawrenceville Borough
  • McClure Township – McClure was formed in 1858 from the section of Ross Township adjacent to Allegheny City. In 1867 McClure, along with sections of Reserve Township, was incorporated into Allegheny City. The McClure section of this annexation became Wards 9 (Woods Run Area) and 11 (present day Brighton Heights) in the City of Pittsburgh.
  • Mifflin Township- comprised the modern day communities of Whitaker, West Mifflin, West Homestead, West Elizabeth, Pleasant Hills, Munhall, Lincoln Place, Jefferson Hills, Homestead, Hays, Duquesne, Dravosburg, Clairton and part of Baldwin.
  • Patton Township – was in east central part of the county, north of North Versailles Township, east of Wilkins and Penn Townships, and south of Plum Township. In U.S. census for 1860–1880. In 1951 it became incorporated as the borough of Monroeville.
  • Northern Liberties Borough – in what is now the Strip District of Pittsburgh. The borough was annexed to Pittsburgh in 1837 as the first addition to the city's original territory.
  • Peebles Township – included most of what is now the eastern part of the city of Pittsburgh from the Monongahela River in the south (today's Hazelwood) to the Allegheny River in the north. It was subdivided into Collins and Liberty townships, all of which were incorporated into Pittsburgh in 1868.
  • Pitt Township
  • St. Clair Township – stretched from the Monongahela River south to the Washington County line. It divided into Lower St. Clair, which eventually became part of the City of Pittsburgh, Dormont, Mount Lebanon, and Upper St. Clair.
  • Snowden – now known as South Park Township.
  • Sterrett Township
  • Temperanceville – what is now Pittsburgh's West End.
  • Union Borough – the area surrounding Temperanceville.
  • West Liberty Borough – now the neighborhoods of Brookline and Beechview in Pittsburgh.

Population ranking

The population ranking of the following table is based on the 2010 census of Allegheny County.

county seat

Rank City/Town/etc. Population (2010 Census) Municipal type Incorporated
1 Pittsburgh 305,704 City 1794 (borough) 1816 (city)
2 Penn Hills 42,329 Municipality 1851 (Penn Twp.) 1958 (Penn Hills Twp.) 1976 (municipality)
3 Mt. Lebanon 33,137 Municipality 1912 (township) 1975 (municipality)
4 Bethel Park 32,313 Municipality 1949 (borough) 1978 (municipality)
5 Monroeville 28,386 Municipality 1951
6 Plum 27,126 Borough 1788 (township) 1956 (borough)
7 Allison Park 21,552 CDP
8 West Mifflin 20,313 Borough 1942
9 Baldwin 19,767 Borough 1950
10 McKeesport 19,731 City 1842 (borough) 1891 (city)
11 Wilkinsburg 15,930 Borough 1871 (Sterrett Twp.) 1887 (borough)
12 Whitehall 13,944 Borough 1948
13 Franklin Park 13,470 Borough
14 Munhall 11,406 Borough
15 Carnot-Moon 11,372 CDP
16 Jefferson Hills 10,619 Borough
17 Brentwood 9,643 Borough 1916
18 Swissvale 8,983 Borough
19 Glenshaw 8,981 CDP
20 Dormont 8,593 Borough 1909
21 Bellevue 8,370 Borough 1867
22 Castle Shannon 8,316 Borough 1919
23 Pleasant Hills 8,268 Borough
24 Carnegie 7,972 Borough 1894
25 White Oak 7,862 Borough
26 Clairton 6,796 City 1903 (borough) 1922 (city)
27 West View 6,771 Borough
28 Forest Hills 6,518 Borough 1919
29 Oakmont 6,303 Borough 1889
30 McKees Rocks 6,104 Borough 1892
31 Crafton 5,951 Borough
32 Coraopolis 5,677 Borough 1886
33 Duquesne 5,565 City 1891 (borough) 1918 (city)
34 Fox Chapel 5,388 Borough
35 Turtle Creek 5,349 Borough
36 Bridgeville 5,148 Borough 1901
37 North Braddock 4,857 Borough
38 Avalon 4,705 Borough 1874
39 Tarentum 4,530 Borough 1842
40 Glassport 4,483 Borough
41 Green Tree 4,432 Borough 1885
42 Sewickley 3,827 Borough
43 Port Vue 3,798 Borough
44 Millvale 3,744 Borough
45 Pitcairn 3,689 Borough
46 Etna 3,451 Borough
47 Sharpsburg 3,446 Borough
48 Springdale 3,405 Borough
49 Mount Oliver 3,403 Borough
50 Ingram 3,330 Borough
51 Brackenridge 3,260 Borough 1901
52 Trafford (mostly in Westmoreland County) 3,174 Borough 1904
53 Homestead 3,165 Borough
54 Edgewood 3,118 Borough 1888
55 Churchill 3,011 Borough
56 Aspinwall 2,801 Borough 1892
57 Gibsonia 2,733 CDP
58 Liberty 2,551 Borough
59 Imperial 2,541 CDP
60 Verona 2,474 Borough 1871
61 Emsworth 2,449 Borough
62 Greenock 2,195 CDP
63 Wilmerding 2,190 Borough
64 Braddock 2,159 Borough 1867
65 McDonald (mostly in Washington County) 2,149 Borough 1889
66 East McKeesport 2,126 Borough
67 Rankin 2,122 Borough
68 West Homestead 1,929 Borough
69 Braddock Hills 1,880 Borough 1946
70 East Pittsburgh 1,822 Borough
71 Dravosburg 1,792 Borough
72 Ben Avon 1,781 Borough 1891
73 Bakerstown 1,761 CDP
74 Cheswick 1,746 Borough
75 Sturgeon 1,710 CDP
76 Edgeworth 1,680 Borough
77 Versailles 1,515 Borough
78 Elizabeth 1,493 Borough
79 Oakdale 1,459 Borough
80 Russellton 1,440 CDP
81 Blawnox 1,432 Borough 1925
82 Bell Acres 1,388 Borough 1960
83 Whitaker 1,271 Borough
84 Heidelberg 1,244 Borough
85 Leetsdale 1,218 Borough
86 Bradford Woods 1,171 Borough 1915
87 Rennerdale 1,150 CDP
88 Lincoln 1,072 Borough
89 Curtisville 1,064 CDP
90 Enlow 1,013 CDP
91 Harwick 899 CDP
92 Sewickley Heights 810 Borough
93 Chalfant 800 Borough
94 Bairdford 698 CDP
95 Pennsbury Village 661 Borough
96 Sewickley Hills 639 Borough
97 Wall 580 Borough
98 Noblestown 575 CDP
99 Glen Osborne 547 Borough
100 Boston 545 CDP
101 West Elizabeth 518 Borough
102 Thornburg 455 Borough
103 Clinton 434 CDP
104 Rosslyn Farms 427 Borough
105 Ben Avon Heights 371 Borough 1913
106 Glenfield 205 Borough
107 Haysville 70 Borough


In the late 18th century farming played a critical role in the growth of the area. There was a surplus of grain due to transportation difficulties in linking with the eastern portion of the state. As a result, the farmers distilled the grain into whiskey, which significantly helped the farmers financially.

Tree Map of Employment by Occupations in Allegheny County, Pa (2015)
Employment by occupation in Allegheny County

The area quickly became a key manufacturing area in the young nation. Coupled with deposits of iron and coal, and the easy access to waterways for barge traffic, the city quickly became one of the most important steel producing areas in the world. Based on 2007 data from the US Army Corps of Engineers, Pittsburgh is the second (after Laredo, Texas) busiest inland port in the nation.

US steel production declined late in the 20th century, and Allegheny County's economy began a shift to other industries. It is presently known for its hospitals, universities, and industrial centers. Despite the decline of heavy industry, Pittsburgh is home to a number of major companies and is ranked in the top ten among US cities hosting headquarters of Fortune 500 corporations, including U.S. Steel Corporation, PNC Financial Services Group, PPG Industries, and H. J. Heinz Company.

The county leads the state in number of defense contractors supplying the U.S. military.



Colleges and universities

Community, junior and technical colleges

  • Bidwell Training Center
  • Community College of Allegheny County
  • Empire Beauty Schools
  • Fountain of Youth Academy of Cosmetology
  • Institute of Medical and Business Careers
  • North Hills Beauty Academy
  • Pittsburgh Career Institute
  • Pittsburgh Institute of Aeronautics
  • Pittsburgh Institute of Mortuary Science
  • Pittsburgh Multicultural Cosmetology Academy
  • Pittsburgh Technical College
  • Rosedale Technical College
  • South Hills Beauty Academy
  • Triangle Tech
  • Vet Tech Institute

Public school districts

Map of Allegheny County Pennsylvania School Districts
Map of Allegheny County, Pennsylvania Public School Districts
  • Allegheny Valley School District
  • Avonworth School District
  • Baldwin-Whitehall School District
  • Bethel Park School District
  • Brentwood Borough School District
  • Carlynton School District
  • Chartiers Valley School District
  • Clairton City School District
  • Cornell School District
  • Deer Lakes School District
  • Duquesne City School District
  • East Allegheny School District
  • Elizabeth Forward School District
  • Fort Cherry School District (part)
  • Fox Chapel Area School District
  • Gateway School District
  • Hampton Township School District
  • Highlands School District
  • Keystone Oaks School District
  • McKeesport Area School District
  • Montour School District
  • Moon Area School District
  • Mount Lebanon School District
  • North Allegheny School District
  • North Hills School District
  • Northgate School District
  • Penn Hills School District
  • Penn-Trafford School District (part)
  • Pine-Richland School District
  • Pittsburgh School District
  • Plum Borough School District
  • Quaker Valley School District
  • Riverview School District
  • Shaler Area School District
  • South Allegheny School District
  • South Fayette Township School District
  • South Park School District
  • Steel Valley School District
  • Sto-Rox School District
  • Upper St. Clair School District
  • West Allegheny School District
  • West Jefferson Hills School District
  • West Mifflin Area School District
  • Wilkinsburg School District
  • Woodland Hills School District

Approved private schools

These private schools provide special education for disabled students:

  • ACLD Tillotson School, Pittsburgh
  • The Day School at The Children's Institute, Pittsburgh
  • DePaul School for Hearing and Speech, Pittsburgh
  • Easter Seal Society of Western Pennsylvania
  • The Education Center at the Watson Institute, Sewickley
  • Pace School, Pittsburgh
  • Pressley Ridge Day School, Pittsburgh
  • Pressley Ridge School for the Deaf, Pittsburgh
  • The Watson Institute Friendship Academy, Pittsburgh
  • Wesley Spectrum Highland Services, Pittsburgh
  • Western Pennsylvania School for Blind Children, Pittsburgh
  • Western Pennsylvania School for the Deaf, Pittsburgh

Private high schools

  • Bishop Canevin High School
  • Central Catholic High School
  • Cornerstone Christian Preparatory Academy
  • Eden Christian Academy
  • The Ellis School
  • Hillcrest Christian Academy
  • Harvest Baptist Academy
  • Imani Christian Academy
  • Oakland Catholic High School
  • Our Lady of the Sacred Heart High School
  • Serra Catholic High School
  • Seton-La Salle Catholic High School
  • Sewickley Academy
  • Shady Side Academy
  • St. Joseph High School
  • Vincentian Academy
  • Winchester Thurston School

Images for kids

See also

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