Boulder County, Colorado Genealogy Records

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

Selected inventory review: 2026-11-02. Selected collection metadata checked against repository catalog descriptions. This is not a complete holdings audit, examination of original records, or certification of current access. See the access note for limitations. Repository catalog or holdings guide

Formed
1861
County seat
Boulder
Adams CountyArapahoe CountyBroomfield CountyClear Creek CountyDenver CountyDouglas CountyEagle CountyElbert CountyGilpin CountyGrand CountyJackson CountyJefferson CountyLarimer CountyPark CountySummit CountyWeld CountyBoulder CountyClear CreekDenverGilpinGrandJeffersonSummitBoulder
Boulder CountyToday's boundaries · U.S. Census Bureau

Listed record inventories

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

Other records

Tax records

Wills and estates

County government

Court records

Marriages, births and deaths

Census records

Naturalization records

Deeds and land

See the repository's descriptions and search options

Repository access note: Selected county and court series from the Colorado State Archives 2013 Finding Aids Quick Index. Only unambiguous dated rows marked Open in that historical index are included. That label does not certify current access. Confirm custody and restrictions with the Archives. Spans summarize separate storage units and may contain gaps.

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

  • Boulder County official website

    Hours, addresses and phone numbers for the county clerk and recorder and the district court, and any online record search the county offers.

  • The county clerk and recorder

    Deeds and other land records, and marriage licenses.

  • The district court

    Probate (wills and estates) in every county but Denver, which has its own probate court, plus divorces and civil cases.

  • The Colorado State Archives

    In Denver: county and court records, territorial records and indexes.

  • Colorado State Archivesfree

    The state archives in Denver, with county, court and territorial records and indexes to many of them.

  • FamilySearch Catalogfree

    Search by place for "Colorado, Boulder" 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 Boulder County: Broomfield County

Colorado TerritoryBoulderBoulderColorado Territory
Boulder as created in 1861Where 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 1861, search the parent county. The Atlas of Historical County Boundaries shows each boundary change.

Research tip

A 1907 law set up statewide registration of births and deaths in Colorado; the state's own records begin with deaths in 1900 and births in 1910. Before 1861 the area was part of Kansas, Nebraska, Utah and New Mexico territories, so an early settler's records can be in any of them.