Armstrong County, Pennsylvania

Armstrong County
Armstrong County Courthouse
Location within the U.S. state of Pennsylvania
Pennsylvania's location within the U.S.
Coordinates: 40°49′N 79°28′W / 40.81°N 79.46°W / 40.81; -79.46
Country United States
State Pennsylvania
FoundedMarch 12, 1800
Named afterJohn Armstrong
SeatKittanning
Largest boroughKittanning
Area
  Total
664 sq mi (1,720 km2)
  Land653 sq mi (1,690 km2)
  Water11 sq mi (30 km2)  1.6%
Population
 (2020)
  Total
65,558
  Estimate 
(2022)
64,747
  Density99/sq mi (38/km2)
Time zoneUTC−5 (Eastern)
  Summer (DST)UTC−4 (EDT)
Congressional district15th
Websitewww.co.armstrong.pa.us
DesignatedOctober 15, 1982

Armstrong County is a county in the Commonwealth of Pennsylvania. As of the 2020 census, the population was 65,558. The county seat is Kittanning. The county was organized on March 12, 1800, from parts of Allegheny, Westmoreland and Lycoming Counties. It was named in honor of John Armstrong, who represented Pennsylvania in the Continental Congress and served as a major general during the Revolutionary War. The county is part of the Greater Pittsburgh region of the commonwealth.