Source Detail


Title Person(s) Vol. Page(s) Date 1 Date 2
Its Formation.


Abbreviation Type Citation
Negley 1876 county histories Negley, W. B. "Allegheny County; its Formation, its Cities, Wards, Boroughs and Townships." Atlas of the County of Allegheny, Penna.. Plate 4. Philadelphia, Pa.: G. M. Hopkins, 1876.

Summarized Source Data

Type Summary
Text ITS FORMATION. September 24, 1788. The County was formed out of parts of Westmoreland and Washington Counties, from which, March 12th, 1800, was taken and formed the Counties of Butler, Crawford, Mercer and Erie, and parts thereof in the formation of the Counties of Beaver, Armstrong, Warren, and March 13th, 1800, Venango. The remaining portion forming the present County of Allegheny.

Event Links

Detail Type Description Successful? Date
View New County Allegheny County 1788 Creation yes Sep 24, 1788
View New County Armstrong County-Beaver County-Butler County-Crawford County-Erie County-Mercer County-Venango County-Warren County 1800 Creation yes+ Mar 12, 1800