From a comparison to other cities perspective, something is weird about DC school enrollment numbers: they are too high

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Updated with data from Boston and Detroit.  I also sent this post to a local e-list on K-12 education and someone asked about Detroit and Boston, opining that DC families may have more children.  Actually, I thought that might be an issue, especially because lower income households tend to have more children than higher income households, but I'd have to dig deep into the data which is more than I want to do...

However, Boston has about 645,000 residents, about the same as DC, and a K-12 student population, including charters, of about 56,000.

Detroit, sadly is close to DC in population, with about 680,000 residents--when I lived in Detroit there were 1.5 million residents!--and the Detroit Public Schools population for FY2015 is about 47,200.
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I looked into this briefly, in response to a thread on a local e-list, where among other points, the writer said we would have to hire thousands and thousands of more teachers as student enrollments increase in the face of DC's plan to achieve a population of 800,000 in about 15 years (2029).

Something is weird about DC public school enrollments. Seattle has roughly the same population as DC (they have 640,000 residents, DC has about 650,000 residents) and 52,000 students in its public school system. Between charter and traditional schools, DC has about 86,000 students, based on preliminary counts in October 2014.

Similarly, San Francisco has a residential population of almost 850,000 and a student population in the public schools of about 55,000.

Part of the problem is that nonresidents with relatives in DC are still enrolling their children in DC schools, and availing themselves of relative-provided child care afterwards. There is a perverse incentive for schools to let this slide, since they are funded on a per student basis.

This has been a problem for decades, and starting in the Williams Administration (late 1990s/early 2000s) DCPS started cracking down on this (which is why enrollments dropped so much at some schools, especially in Northeast DC). But I still see an awful lot of cars with Maryland license plates dropping kids off at school when I happen to be biking by schools in the morning.

An element which boosts reports of school enrollment in DC is the fact that DC offers the nation's most comprehensive pre-K program for children aged three to four years. DC is a national leader in pre-K public education, which is a good thing. Although it boosts enrollment numbers and costs.

According to "A portrait of universal pre-kindergarten in DC" from the Urban Institute, in 2013, not quite 12,000 3 and 4 year olds were enrolled in DC pre-K education. Even taking that into account, DC has 40% more children in public schools than Seattle, even though the cities have roughly the same population.

Again, potentially DC's pre-K program incentivizes--who wouldn't want to avoid the cost of two years worth of childcare?--nonresidents with relatives in DC to try to get their kids into the public school system, but I don't have any first hand experience with whether or not this is an issue.

Part of the difference between DC and San Francisco would be the cost of housing. Families tend to prefer larger houses and lots, and in SF, the cost of such properties is precipitous, double, triple or quadruple the cost of equivalent properties in DC (you can buy big houses with big lots in many neighborhoods in DC for $450,000 to $800,000, you can't in SF).