Guarding Science

Security at the Lab before and after World War II.

By Angie Piccolo | August 29, 2022

Guarding Science Feature Opt

Badges, checkpoints, security clearances, and a fence that completely surrounded the town. From Day 1 — and for nearly 80 years since then — security at the Lab has been paramount.

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This badge photo of J. Robert Oppenheimer, the Lab’s first director, shows Oppenheimer’s white round button, which indicated he had the highest level of security clearance.

Security during World War II was important to maintaining the secrecy of the Manhattan Project, the government’s wartime effort to create the atomic bomb. It started with choosing a clandestine location.

Physicist J. Robert Oppenheimer, the Lab’s first director, and General Leslie Groves, head of the Manhattan Project, needed a secluded place to build the Lab. They ultimately decided on the mesa on top of Pajarito Plateau after considering several factors, including:

  • The small number of inhabitants (a boys’ boarding school and a few homesteaders)
  • The area’s regional isolation and distance from the coast and large cities
  • The easily protected nature of the location.
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Lab facilities and the town itself were hastily constructed, though security to protect the top-secret work was never sacrificed.

Security and Restrictions

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Los Alamos Project Main Gate

A nearly 10-foot-tall barbed wire fence was built to surround the Lab’s technical areas and adjacent community, where Lab staff and their families lived. Military personnel guarded the entrances to the town 24-hours a day, seven days a week, checking gate passes and controlling who could enter the town.

Incoming mail and other official documents, such as driver’s licenses, death certificates, and birth certificates all listed the address P.O. Box 1663 rather than a city name so as not to draw attention to the newly established community.

Restrictions were imposed on scientists and their families to closely monitor their comings and goings. For example, residents had to register travel plans and present their passes at the guarded entry gates in order to travel.

To gain access to the Lab’s technical areas and classified knowledge, staff underwent extensive background checks and were assigned color-coded badges indicating their need-to-know and clearance level.

  • White round buttons with blue passes (see Oppenheimer’s badge photo above) indicated the highest level of clearance and were granted to the scientific and administrative staff and their secretaries.
  • Round bronze metal buttons and white passes were assigned to steam-plant operators.
  • White oblong buttons with letters and temporary passes were given to official visitors.

The strict security measures, however, were not completely foolproof. In a documentary interview, Richard Feynman, a Lab physicist, Nobel Prize winner, and notorious prankster, recalled: “There would be big holes in the outside fence that a man could walk through standing up and I used to enjoy going out through the gate and coming in through the fence hole and going out through the gate again and in through the fence hole until the poor sergeant at the gate would gradually realize this guy’s come outta the place without going in once.”

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Even after the end of World War II in 1945, security remained paramount. Checkpoints, such as the one shown in this photo from 1951, remained and are still in place today.

Post-World War II

At the end of World War II, the Manhattan Project and the town of Los Alamos were no longer a secret — the two Lab-created atomic bombs had been deployed, helping end history’s deadliest conflict on September 2, 1945.

In the months after the war, travel restrictions for residents were removed and access to the town was relaxed. Nonresidents were now allowed to enter the town, but only by invitation. Also, residents could now take photographs in town, although still not within any of the Lab’s technical areas. Meanwhile, the Lab’s main technical area moved to the south mesa where more space was available for new permanent buildings.

Meanwhile, security evolved in order to meet the changing needs of the Lab’s nuclear scientific research. For example, the Atomic Energy Commission (AEC), which took over control of the Lab in 1947, retained the surrounding fence but replaced the military personnel with civilian guards to secure the entrance gates.

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After World War II ended in 1945, the Lab and Los Alamos were no longer a secret. However, security measures have remained through today, evolving to address the needs of the Lab’s national security mission through its nearly 80-year history.

Cold War Years

Guarded checkpoints and security clearances remained as scientific nuclear research and weapons development continued into the Cold War (1947-1989). Badges are still required in order to enter into certain areas today.

“There weren’t dramatic changes in security clearance policies or badging after World War II except for cosmetic changes to the badges themselves. We still have classification categories based on the 'need-to-know' and, then as now, people were vetted following a personnel security review process.” —Ellen McGehee, Lab Historian

The AEC considered removing fences and gates surrounding the town in the early 1950s, but hesitated due to the ongoing development of the hydrogen bomb and the tense nature of the Cold War. Meanwhile, Los Alamos’s sister laboratories in Oak Ridge, Tennessee, and Hanford, Washington, became more open in 1953, with a fence surrounding Oak Ridge coming down four years earlier in 1949.

Eventually, the government decided that it was too expensive to maintain the gates into Los Alamos, although some of the residents resisted, arguing for the “safety of children and grandmothers,” according to the book Inventing Los Alamos: The Growth of an Atomic Community by Jon Hunner.

The fences, however, came down on February 18, 1957. The main guard station was replaced by a drive-in burger restaurant for a period of time. Los Alamos, a secret city for more than two years and a closed city for 15 years, was now open to the public. 🔎