Family separation at the border is not a cost-cutting measure for President Donald Trump: Newly created “tent cities” for migrant children being separated from their parents cost $775 per night per person, according to a new report. That’s two to three times what it costs to put them in a permanent facility or to keep them with their parents.

NBC News’s Julia Ainsley, citing an official at the Department of Health and Human Services, reported on Wednesday that the “tent cities” the US government is setting up to hold the influx of migrant children cost nearly $800 per night, much more than other alternatives. There’s a lot of urgency to get these temporary facilities up and running fast, and bringing in security, air conditioning, medical workers, and other government contractors at such a pace is expensive.

For comparison, NBC News reports holding a child in a permanent HHS facility in Brownsville, Texas, costs $256 per night per person. And keeping kids with their parents in a detention center costs about $298 per resident per night.

In other words, it’s most cost-effective to keep kids with their parents or, at the very least, in preexisting facilities.

The HHS official told NBC News it is “aggressively looking for more potential sites” for tent cities as more and more children arrive. More than 2,300 children have been taken from their parents at the US-Mexico border since the Trump administration announced its “zero tolerance” policy for illegal entry in May. More than 11,000 immigrants under the age of 18 are in custody.

The tent cities aren’t good, but it’s not clear if there are better alternatives

The image created by tent cities is not a pretty one, and the idea of putting children in essentially outdoor camps is disturbing. But the actual scenario might be a lot more complicated, as Vox’s Dara Lind recently explained.

The Flores settlement, a court order that’s been in place for decades, requires that immigrant children in custody be placed with a close family or friend “without unnecessary delay,” and if there isn’t a family or friend, children have to be kept in the “least restrictive” form of custody possible.

The government might prefer to actually keep families together in immigrant detention, in part because of costs. And keeping families together makes deporting all of them at once easier if they aren’t granted asylum.

The Trump administration has blamed the Flores settlement for its separation of families, but of course, it’s not required to split up children and parents. As Lind explains, though, the imagery of “tent cities” is more complicated than meets the eye: