For most of the last two decades, San Francisco has been among the country's least age-diverse places, boasting one of the lowest concentration of families with children under 18 of any major US city. That figure, which hovered around 15 percent in the 2000s, is now estimated to be 13 percent, and the New York Times again takes up the topic, which some view as a kind of crisis about what the city's future looks like if we continue to have fewer and fewer kids among us.
There's also the argument for how we keep diverse types of housing, especially affordable housing, in San Francisco if so many people are co-habitating in roommate situations, effectively driving up market-rate rents for larger apartments because they are all wage earners in the prime of their lives paying separate rents as opposed to families with children trying to survive on a maximum of two incomes, or just one. A new Planning Department report released just week found that just 30 percent of three-bedroom homes in the city are currently occupied by families, but it cautions that the trend of families leaving the city to move to the east and elsewhere as soon as they have school-age kids may reverse as Millennials who value urban amenities opt to stay put and raise kids here even if that seems utterly unaffordable to many now.
The NYT notes that a recent figure on California as a whole shows the lowest birthrate, statewide, since the Great Depression, but cities without kids aren't necessarily cities we all want to live in. The paper talks to young couple Daisy Yeung, a high school teacher, and Slin Lee, who live in a studio apartment near the Castro with their small dog, and while they intend to have kids, they don't think they'll want to do it in the city.
Add to the unaffordability of housing the uneven quality of SF's public schools itself arguably a product of there being so few middle class families and the lack of backyards and places for kids to run free and safe, and the trend toward suburbia for SF families is likely to continue for the foreseeable future.
As of the 2010 census, the trend showed a slight uptick in the number of children under 5 living in SF, probably just concurrent with population growth, but an outward migration of kids 5 to 18 over the previous decade.
The Planning report notes that the city has an opportunity in the coming decade to address the issue, but it will come with the acceptance that neighborhoods have to become more dense. "An astonishing 72% of the city’s privately owned parcels are zoned for single-family housing (RH-1) and two-unit housing (RH-2)," says the report. "This puts the burden of population growth on the remaining 28% of parcels, which already houses all of our businesses, institutions, and mixed-use housing." And thus you have a huge segment of the city's single population in their 20s and 30s who stick to a relatively small number of neighborhoods: the Mission, Castro, SoMa, Hayes Valley, Tenderloin, NoPa, and the Marina.
Note that in 1970, San Francisco was much closer to the national average in terms of children, with about 22 percent of the population under 18. These days, with us at 13 percent, New York City is the second lowest with 21 percent, and Chicago right at the national average of 23 percent.
At a current population of 865,000, we have 120,000 kids, and roughly the same number of dogs i.e. half of our "childless" families do, indeed, have kids they have to walk on leashes.