Marin county's population is shrinking the fastest in the Bay Area. Reason? No kids.
San Francisco Chronicle / 2-8-23
SNIP
Of all the Bay Area counties, only San Francisco has lost more of its population overall since 2019, about 4.4% to Marin’s 3.5%. But Marin has been losing people since 2017, well before the pandemic ushered tens of thousands of 20-something San Franciscans out of the city.
One reason why Marin County lost population, experts said, is that its residents haven’t had a lot of kids lately — nor are they likely to.
The county’s median age of 46.9 years is the highest of any Bay Area county, and more than nine years higher than the state overall, according to the 2021 American Community Survey. This means Marin sees more deaths and fewer births than other counties, said Hans Johnson, Senior Fellow at the Public Policy Institute of California who studies population change.
LINK (paywall): https://www.sfchronicle.com/bayarea/article/marin-county-california-population-17769766.php
Interesting. Though relocation is mostly cited to explain the state exodus, demographics also play a role.