Where to find the records
- Allegheny County official website
Hours, addresses and phone numbers for the recorder of deeds, the register of wills, the clerk of the orphans' court and the prothonotary, and any online record search the county offers.
- The recorder of deeds
Deeds and mortgages, from the county's beginning.
- The register of wills
Wills and estate administrations. County birth and death registers for 1893 to 1906 are usually here or with the clerk of the orphans' court (often the same person); statewide registration began in 1906.
- The clerk of the orphans' court
Marriage licenses from the fall of 1885, plus guardianships and the division of estates among heirs.
- The prothonotary
Civil court records, and in many counties, naturalization records.
- The Pennsylvania State Archives
Land warrants and surveys for the first purchases of land from the Penns and the Commonwealth, tax lists, and microfilm of many county records.
- Pennsylvania State Archivesfree
The state archives in Harrisburg: land warrants and surveys, tax lists, military records and microfilm of county records.
- FamilySearch Catalogfree
Search by place for "Pennsylvania, Allegheny" to find filmed and digitized records, many viewable free online with a FamilySearch account.
Offices change their hours and access rules; call before you visit.
Boundaries and parent counties
Formed from: Northumberland County, Washington County, Westmoreland County
Check the parent counties for earlier records: Northumberland County, Washington County, Westmoreland County
Later formed partly from Allegheny County: Armstrong County, Beaver County, Butler County, Crawford County, Erie County, Mercer County, Venango County, Warren County
Records stay with the county that created them. If your ancestor lived here before 1788, search the parent county. The Atlas of Historical County Boundaries shows each boundary change.
Research tip
Pennsylvania counties didn't issue marriage licenses until the fall of 1885, so earlier marriages are mostly in church records. Lutheran, Reformed, Presbyterian and Quaker registers are often the best source.