Union County, Ohio Genealogy Records

Selected record inventories for Union County, their listed years, and where to ask for access.

Selected inventory review: 2026-11-02. Selected catalog metadata extracted from the linked sources. This is not an examination of original records, a complete county holdings audit, or certification of current access. Historical sources are identified in the access note. Ohio Genealogical Society 2012 inventory

Formed
1820
County seat
Marysville
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Union CountyParent counties (search here for earlier records)Today's boundaries · U.S. Census Bureau

Listed record inventories

Selected holdings and indexes for Union County, checked against the repository descriptions linked below. Date spans may contain gaps; an index is not a complete set of original records.

Census records

Poor relief and institutions

Other records

Marriages, births and deaths

See the repository's descriptions and search options

Repository access note: Selected microfilm holdings from the Ohio Genealogical Society’s published 2012 inventory. This is a historical inventory: confirm that the film is still available, along with current visit, copying and access conditions, before relying on it. These are holdings at the society, not a complete county courthouse inventory. Census spans do not imply that every census survives; the 1890 population census is largely lost. Some original catalog titles contain historical terminology.

Sources: the catalogs and repository descriptions linked on the entries above. Selected inventories do not establish complete coverage of every record type or online access to original documents. Read the repository access note for source dates and limitations.

Where to find the records

  • Union County official website

    Hours, addresses and phone numbers for the county recorder, the probate court, the clerk of the court of common pleas and the Ohio History Connection, and any online record search the county offers.

  • The county recorder

    Deeds, mortgages and other land records.

  • The probate court

    Wills, estates and guardianships, marriage licenses, births and deaths registered from 1867 to 1908, and most naturalizations from about 1859 to 1906.

  • The clerk of the court of common pleas

    Civil cases, divorces, and naturalizations before about 1859 and after 1906.

  • The Ohio History Connection

    In Columbus: state records, death certificates, and county records at its archives and regional network.

  • Ohio History Connection Archives & Libraryfree

    The state's historical society archives and library in Columbus, with state and county records and death certificates.

  • FamilySearch Catalogfree

    Search by place for "Ohio, Union" 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: Delaware County, Franklin County, Logan County, Madison County

Check the parent counties for earlier records: Delaware County, Franklin County, Logan County, Madison County

ChampaignFairfieldClarkNon-County Area 7DelawareNon-County Area 5FranklinNon-County Area 9LoganMadisonUnionUnionDelawareNon-County Area 5FranklinNon-County Area 9LoganMadisonChampaign
Union as created in 1820Where its land was the day beforeToday's boundaryBoundaries: Newberry Library, Atlas of Historical County Boundaries

Records stay with the county that created them. If your ancestor lived here before 1820, search the parent county. The Atlas of Historical County Boundaries shows each boundary change.

Research tip

Ohio's probate courts registered births and deaths from 1867 until statewide registration began in 1908, so for those years ask the probate court of the county.