Latinos account for 34.28 percent of the Napa County population, Asians 7.95 percent and African Americans 2.16 percent, according to the study conducted by the Haas Institute for a Fair and Inclusive Society, a research and social justice center at UC Berkeley. Combined, their numbers approach the white, non-Latino population of the county, 52.28 percent out of the 140,973 listed in a 2017 U.S. Census Bureau estimate.

Authors Stephen Menendian and Samir Gambhir released their findings in the first two segments of a planned five-part study, including an analysis of Bay Area segregation published in October and a report on the demographics of regional counties released Feb. 6.

Gambhir and Menendian reported sharp differences in the distribution of racial groups across Napa County — a pattern they wrote is repeated in other Bay Area communities where diversity in the aggregate often masks segregation between cities and even neighborhoods.

American Canyon, for example, hosts the county’s largest share of Asians and African Americans — 35.1 and 8 percent of the city population, respectively. At the opposite end of the county, the most concentrated Latino population is found in Calistoga with 47.5 percent of the total.

The largest white majority was reported in Yountville, where they account for 82.2 percent of residents in the tourism-driven town, the county’s smallest by population at less than 3,000.

The Haas Institute study identified the city of Napa as the county’s most diverse at 55 percent white and 39 percent Latino, with Asians accounting for 3 percent of the population and African Americans 1 percent.

Overall, the nine-county Bay Area is about 39 percent white, 26 percent Asian, 24 percent Latino and 6 percent black, with 5 percent classified as multiracial, Native American, Pacific Islander or belonging to other groups, the Haas report states.

However, the study’s authors argue such big-picture numbers conceal the disparities in housing, educational and other opportunities that have persisted even decades after sweeping civil rights legislation — a problem they connect to historical racial disparities between cities and neighborhoods.

“More than 60 years since the Supreme Court’s landmark Brown v. Board of Education decision denounced racial segregation in primary and secondary public schools, and 50 years since the enactment of the federal Fair Housing Act, our neighborhoods and schools have yet to reflect the rich diversity of our nation as a whole,” the authors wrote in their opening brief Oct. 29.

“… These segregated residential patterns shape the life chances of its residents, who not only reside in racially segregated neighborhoods, but attend racially segregated schools and have racially differentiated access to a plethora of public and private resources as well.”

Demographic numbers point to larger shares of minority residents in Alameda, San Mateo and Santa Clara counties — as high as 68.69 percent in Alameda County — but less diversity in Napa and the North Bay. Whites make up 62.14 percent of the population in Sonoma County and 70.32 percent in Marin, the largest such share in the Bay Area, according to the report.

The remaining three portions of the Haas Institute study will focus on measuring segregation and integration; the effects of segregation on education, health and economic opportunity; and policy principles for increasing racial integration.