PO Box 1663 by Delaney Hall

In the early 1940s, the town now known as Los Alamos, NM was selected as the site for a top-secret atomic weapons lab. The area was remote and there was an old boys’ school there that could be repurposed into living quarters for the physicists, explosives experts, and military personnel who would go on to develop the first nuclear bomb.

Establishing a new, top-secret laboratory in the middle of nowhere was a logistical challenge. Not only did the government need to build a small town, they needed to import particle accelerators, a cyclotron, and all the other high-tech equipment necessary for bomb-building. They had to recruit not just dozens of scientists, but also machinists, glass-blowers, engineers, and other technicians. They had to get all this equipment — and all these people — to the top of a steep mesa about 30 miles northwest of Santa Fe, accessible only by a small road that climbed up to the top of the mesa.

The site of this new laboratory was, at the time, one of the country’s most closely guarded military secrets and there were various ways that government officials maintained the secrecy of the isolated plateau. The town wasn’t listed on any map, and the people who went to live and work there weren’t allowed to tell friends or family members what their work involved.

Scientists referred to Los Alamos as “The Hill.” Military members called it “Project Y.” And just two post office boxes — PO Box 1663 for civilians and PO Box 1539 for the military, both in Santa Fe, NM — served the entire town.

Many of the people who worked on the Manhattan Project at Los Alamos were young. “The average age was 29,” says Alan Carr, the senior historian at LANL. “There were a lot of young single people here. There were a lot of young couples.” And as it turned out, having so many young people working on the project presented some unexpected security challenges. For one thing, quite a few people ended up having children while living in Los Alamos — a place that wasn’t even supposed to officially exist.

“All of a sudden you went from a locale in New Mexico where no children were ever born — hardly at all — to eight births a month. That looks awfully suspicious if you’re doing the paperwork down in Santa Fe. Why are all these kids being born in Los Alamos?!” says Carr.

So in an effort to maintain secrecy, babies didn’t have “Los Alamos” named on their birth certificates. Instead, their place of birth was listed as “PO Box 1663.” Carr estimates that 100 to 150 children were born at the PO Box.