Marin was among the Bay Area counties with the largest outward migration after the start of the pandemic, according to a new report.

Since the COVID-19 crisis began, the number of people who have left California has decreased by 38%. Not so in the Bay Area, which remained one of the few regions that has seen an uptick in residents relocating, according to the California Policy Lab, a research institute based at the University of California.

Marin ranked No. 4 in the region, with an exit rate of 24% in the first four months of 2020, outpacing Contra Costa and Sonoma counties — at 22.2 % and 20.9%, respectively. San Francisco tops the list of the most exited counties, at 37.9%

Marin residents also moved at a 5.2% higher rate than they did pre-pandemic, compared to Contra Costa County at 1% and Alameda County at 6%.

The Bay Area had been one of the top four destination regions in the state, attracting new residents between 2016 and just before the pandemic, according to the report, which was released Dec. 15. Tens of thousands of people flocked to the area for high-paying tech jobs despite high housing costs.

Analysts say the report corresponds with a recent trend of population loss. Marin lost 1% of residents in 2020, or 2,614 people, according to the California Department of Finance. The highest losses were in unincorporated areas, at 2.6%, or 1,809 people, and in San Rafael at 0.6%, or 369 residents.

Mike Blakeley, chief executive of the Marin Economic Forum, said the reason for the defections is unclear.

“It’s really hard to know why it occurred,” he said “The flow of people in and out of Marin is really an individual choice.”

Blakeley said relocation might have been prompted by an ability to work remotely or for quality of life and affordability.

Cynthia Murray, chief executive of the North Bay Leadership Council, said the report’s significant finding is in “the steep drop in people choosing to locate to Marin, which exacerbates the residents choosing to move out of Marin.”

Those factors combined may have a significant impact on the availability of Marin’s workforce and economic vitality, she said.

Caroline Peattie, executive director of Fair Housing Advocates of Northern California, said she thinks the high exit rate seems connected to concerns about affordability and racial disparity.

Marin home values continued to soar, reaching an average of $1.5 million for a single-family home, a 15.8% increase over last year, according to the real estate data firm Zillow. Rental prices rebounded to more than 6% higher than before the pandemic — with the average apartment priced at $2,683, according to real estate data provider CoStar Group.

”My major concern from a fair housing perspective is that the lack of affordable housing means we will continue to become a less diverse county,” Peattie said.

“Particularly given the recent Race Counts Marin report, this is something Marin County should be focusing on,” she said, referring to a study of inequity. “We need to do more to affirmatively further fair housing.”

Steve Levy, director of the Palo Alto-based Lab for Continuing Study of the California Economy, said the Bay Area’s cost of living is a key factor.

“We continue to be very expensive,” Levy said. “Except for very high-income people, it’s not surprising that the number of people dropped.”

But Levy thinks the trend could reverse, noting that the Bay Area has had an increase in the number of residences for low- and medium-income people.

Marin cities and towns continue to struggle to meet state mandates to increase housing stock.

“The main factor in both exits and entrances is the high cost of living in Marin, especially due to the high cost of housing,” Murray said. “It has been a growing trend that the pandemic accelerated that those whose work allowed them to work remotely or are able to find other employment have been relocating to areas of higher affordability and lower cost of living.”

“As long as Marin doesn’t build more workforce housing, we can expect growing families to move to where housing meets their financial needs and for outsiders to avoid the inflated housing prices in Marin,” she said.

Bay Area News Group contributed to this report.