Contra Costa County, California Genealogy Records

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

Selected inventory review: 2026-11-02. Selected newspaper catalog metadata checked for state and county attribution. Publication dates do not establish complete issue holdings or online access. Library of Congress newspaper directory

Formed
1850
County seat
Martinez
Alameda CountyAmador CountyCalaveras CountyEl Dorado CountyFresno CountyLake CountyMarin CountyMerced CountyNapa CountySacramento CountySan Francisco CountySan Joaquin CountySan Mateo CountySanta Clara CountySanta Cruz CountySolano CountySonoma CountyStanislaus CountyYolo CountyContra Costa CountyAlamedaMarinMercedNapaSan JoaquinSan MateoSanta ClaraSolanoSonomaStanislausContra Costa
Contra Costa CountyToday's boundaries · U.S. Census Bureau

Listed record inventories

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

Newspapers

See the repository's descriptions and search options

Repository access note: Selected newspaper titles cataloged by the Library of Congress with explicit county geography. Priority is given to titles beginning by 1950; up to five later titles are included where no earlier dated title is listed for that county. Dates describe publication history, not the issues available at a library. Multiple format records with the same title, place and dates are grouped. The catalog may describe paper, microfilm or online resources. Open ends and the word Current reflect the catalog description; confirm present availability and exact holdings with the libraries listed on the linked record.

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

  • Find Contra Costa County's official website

    We haven't checked this county's website yet, so this opens a web search. Look for an address ending in .gov, then find the county recorder and the superior court.

  • The county recorder

    Deeds and other land records, and copies of birth, death and marriage records registered in the county.

  • The superior court

    Probate (wills and estates), divorces, adoptions and civil cases; older files may be at the county archives or historical society.

  • The California State Archives

    In Sacramento: state government records, including some court and prison records. The Great Registers of voters on microfilm are at the California State Library, also in Sacramento.

  • California State Archivesfree

    The state archives in Sacramento, with state government records, legislative papers and other collections.

  • FamilySearch Catalogfree

    Search by place for "California, Contra Costa" 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: Land not yet in any county

Later formed partly from Contra Costa County: Alameda County

Contra CostaContra Costa
Contra Costa as created in 1850Today's boundaryBoundaries: Newberry Library, Atlas of Historical County Boundaries

Records stay with the county that created them. If your ancestor lived here before 1850, search the parent county. The Atlas of Historical County Boundaries shows each boundary change.

Research tip

California began statewide registration of births and deaths in 1905. For the years before, look at the county's own registers, church records, and the Great Registers of voters (from 1866), which give each voter's age, birthplace and naturalization.