The 94-year-old deed to a Bolinas cottage asserts that the Big Mesa home cannot be leased, rented, occupied or used by “asiatics, orientals, Africans, or persons of descent from any of said races, or any persons other than of the Caucasian race.” In Seadrift, more than a dozen beach houses cannot be occupied by “any person other than a person of the Caucasian race,” according to their 1949 covenants. On Redwood Drive in Woodacre, the 1927 deed to a shingled bungalow contains a similar restriction. 

This racist language is just the tip of the iceberg, according to Marin officials working to uncover and redact restrictive covenants. Though they haven’t been legally enforceable for decades, the rules still exist on thousands of deeds to homes across the whitest county in the Bay Area.

“It’s a lot more than you think,” said Gordon Tinsley, a supervisor in the Assessor-Recorder-Clerk’s office. A map released by the county last week shows only about a quarter of the homes with restrictive covenants his staff has found so far, he said.

Of the roughly 5,000 restrictive covenants staff have found, few have been corrected. Most of the redlining spanned suburban east Marin from Sausalito up to Novato, with especially large concentrations in Greenbrae and Kentfield. 

In West Marin’s sparse expanse of farmhouses and summer cottages, fewer homeowners were subject to the kind of covenants that often accompanied early suburban development. But the county has found racist deeds in Bolinas, Woodacre, Muir Beach and the Stinson Beach development of Seadrift. 

In Bolinas, the gridded street plan that overlays the Big Mesa was designed in the 1920s by New York developers Arthur and Ruth Smadbeck. They planned a deal that has become the stuff of legend: to offer resort homes in the “Bolinas Beach” subdivision for the price of a subscription to the San Francisco Evening Bulletin. The scheme fell through when the Depression hit, but not before the Smadbecks divided hundreds of parcels, adding racist covenants to each. Dozens of Bolinas homeowners can today find the restrictions on their home documents. 

The Lagunitas Development Company, which once owned much of the San Geronimo Valley, included racist restrictions on the homes it built in the 1910s, ‘20s and ‘30s. The county’s map shows just one valley parcel, a 1927 home in Woodacre, with a deed restriction barring people “other than of the Caucasian race.” But the same sort of restriction once applied to homes across Woodacre, Forest Knolls and Lagunitas, though it was not always enforced in private sales. 

In the 1950s, Seadrift became the last West Marin development to restrict homeownership to whites. William Kent, Jr., son of congressman and early conservationist William Kent, developed the spit that the family had purchased at the turn of the century into 350 homes.

The era of restrictive covenants ended with the passage of the 1968 Fair Housing Act, which prohibited overt discrimination by landlords and real estate companies based on race, religion, sex, national origin, familial status or disability. In California, racist language on new deeds had continued into the 1960s, despite the Supreme Court ruling in 1948 that such language was unconstitutional.

Marin’s efforts were spurred by Assembly Bill 1466, signed by Gov. Gavin Newsom last year, which requires county recorders to identify and redact racist language on property records, shifting the responsibility away from individual property owners. The bill, which was initially opposed by the California Land Title Association, also requires title and escrow companies to inform buyers and sellers of restrictive covenants.

Since last year, the county has altered real estate documents for 55 subdivisions in Marin, covering more than 800 parcels. The process could take years to complete. Mr. Tinsley said all property documents from the 1850s until roughly 1918 are handwritten, and many parcels were organized by a “metes and bounds” system of natural landmarks.

Marin is still deeply segregated, and most of the census tracts with restrictive covenants are still whiter than the county as a whole. This week, the California Department of Housing and Community Development sent feedback on Marin’s updated Housing Element, the eight-year strategy for meeting state-allocated housing needs. The county largely met its mandate to address housing equity in the plan, according to a letter from the H.C.D., but should include more specific analysis of areas of concentrated poverty and high segregation and more discussion of historical land use, zoning and “barriers to housing choices,” including redlining and restrictive covenants.

In a presentation to the Board of Supervisors on Tuesday, Tom Lai, director of the county’s Community Development Agency, drew links between racist exclusion and the contemporary obstruction of affordable housing, citing phrases like “protect the character of our neighborhood” and “uphold our high property values.” 

“These are dog whistle terms that basically say: ‘We need to find ways to exclude those who don’t look like us or who don’t make as much income as us from living amongst us,’” Mr. Lai said. 

Some public comments condemned the A.B. 1466 program as purely symbolic. “This is an incredibly performative exercise,” activist Eva Chrysanthe said. “There is no restitution whatsoever.”