New Mexico: Los Alamos Summary

  • Last updated on November 10, 2022

Because of its isolation, the federal government in November, 1942, chose Los Alamos to be the site for the construction of the first atomic bomb. The atomic bombs that destroyed Hiroshima and Nagasaki in August, 1945, were assembled there. Since its beginning, the University of California, under contract with the Atomic Energy Commission, has continuously operated at this site in its research in atomic energy. Today, a community has grown up around the Los Alamos Laboratory.

Site Office

Los Alamos National Laboratory

P.O. Box 1663

Los Alamos, NM 87545

ph.: (505) 667-5061

Web site:


In mid-1942, the U.S. government, hoping to bring an end to World War II, stepped up its efforts to develop an atomic bomb. The military situation looked grim for the United States and its allies in its all-out war with Germany, Japan, and Italy. The country had not fully recovered from the shock of the Japanese attack on Pearl Harbor in late 1941, and Japan was still in control of the Pacific Ocean. Meanwhile, American troops were pinned down in North Africa. Although it had lost important battles at El Alamain in 1942 and Stalingrad in 1943, Germany still looked as if it could win the war.

The German Bomb Threat

The Allies, moreover, had evidence that German scientists were working on an atomic bomb of their own. The Allies’ suspicions were aroused when they learned that Germany had stopped the sale of uranium, a vital element in the bomb, from the rich mines of Joachimsthal, Czechoslovakia, a region under its control. The Allies’ fears were confirmed by Albert Einstein, Edward Teller, and Leo Szilard, refugee scientists from Europe, who a few years earlier had written to President Franklin D. Roosevelt, warning of the enormous threat posed by German development of the atomic bomb.

President Roosevelt took the scientists’ warning seriously and on October 12, 1939, created the secret Advisory Committee on Uranium. The United States had officially entered the race for the bomb. The committee consisted of three government officials: Lynan Briggs, director of the National Bureau of Standards, and as such, the government’s senior scientist; and two other military officers, representing the army’s and navy’s ordinance divisions. To conduct basic research on the atomic bomb, the committee, on the advice of scientists Szilard, Teller, and Eugene Wigner, acquired four tons of graphite and fifty tons of refined uranium ore.

By 1940, the facts of fission were common knowledge not only to the Germans but to other physicists throughout the world as well. British and American scientists judged it unwise to continue publishing new results. At the urging of Teller, Szilard, and Wigner, the Allies implemented a self-imposed news blackout and began working to develop an atomic bomb to be used in the war.

In building an atomic bomb, the Allies were faced with a major challenge–finding enough uranium, fission’s vital material. With the Joachimsthal mines in German hands, the Allies turned to another large source: Belgium’s African colony of the Congo. In June, 1940, twelve hundred tons of high-grade ore were transferred by freighter from the Congo via Belgium to New York City and a Staten Island warehouse for storage. Before the war’s end, the United States would receive over twenty additional ore shipments from the Congo. The Allies, however, were taking no chances. At about the same time, they began to produce plutonium (Pu-239), which they believed would be superior to the uranium isotope (U-235).

Building a Bomb

By December, 1942, a Chicago-based group of scientists under the direction of Enrico Fermi succeeded in producing the world’s first human-made nuclear chain reaction. There was still no fissionable material for building the atomic bomb because the construction of the plants at which the materials were to be produced had not yet begun.

Additional research also had to be done to supply missing information crucial to making the atomic bomb. Responsibility for the secret research program was assigned to the U.S. Army Corps of Engineers–its code name, “Manhattan Project.” Put under the direction of Dr. J. Robert Oppenheimer, the project eventually involved a workforce of over 100,000 persons and took nearly three years to complete. It was located in New Mexico and served, in the words of I. I. Rabi, as “the first line of defense of the United States.” This was the beginning of the Los Alamos Laboratory, or Project Y.

Los Alamos Laboratory is located on the Pajarito Plateau of New Mexico’s Janoy Mountains. The area’s first permanent settlers, mostly farmers, arrived in the area about 1911. It also became the site of a tuberculosis convalescent center, which attracted people from the industrial East. From 1918, the Los Alamos Ranch served as a school for young boys. The school thrived, and by the 1930’s it had forty-five students.

Oppenheimer and Los Alamos

Robert Oppenheimer’s summer home was across the valley from Los Alamos, and he would often visit the school. Asked to advise the corps on the selection of the atomic bomb research laboratory a few years later, the noted scientist recommended the Los Alamos site. When the military officials inspected Los Alamos, they concluded that it did indeed offer many advantages. It could adequately accommodate the thirty scientists expected to work on the project, and the land could be easily acquired in secrecy. Los Alamos was large and isolated; experiments could be conducted under secure and safe conditions.

In December, 1942, the U.S. government used condemnation proceedings to close the school. The property had to be vacated by mid-February, 1943. The government appropriated more than forty-five thousand acres from government agencies, mostly the Forest Service, and made plans to buy approximately nine thousand privately owned acres. The residents were never told why they were being forced to move. In all, thirty farm families were evicted and their farmland appropriated.

The U.S. government paid $275,000 for the boys’ school. The school’s owner, A. J. Connell, thought it was worth at least $400,000, and went to court. At the end of 1943 a federal court ruled that Connell should receive $375,000 and $7,884 in interest. The settlement and the way the government conducted the confiscation made Connell bitter. He later wrote to a former headmaster of the school, “There are many sides to the taking of Los Alamos. They stopped a growing concern in the middle of its operation, which could not be moved.”

In January, 1943, the government selected the University of California to operate the laboratory at Los Alamos, and soon after, the university signed a contract with the Manhattan Engineering District of the Army. By early spring the project was ready to begin operation.

Life at Los Alamos

Life was difficult for the scientists who took the challenge of developing an atomic bomb at isolated Los Alamos. Security was so tight that not even the scientists’ wives were told what their husbands were doing at the laboratory. Housing, moreover, was substandard and always in short supply. As historian Hal Rothman describes the situation,

Except for the row of home cottages that previously housed the ranch school faculty and had been reserved for the royalty of the world of science, most people lived in green, barracks-like, military-built, four-unit apartments. The water tower, a fixture in southwestern towns, was the only identifying feature of the community.

There was little in the way of entertainment, never enough water, censorship of outgoing mail, and insufficient telephone lines. The project was surrounded by barbed wire and armed guards. The first resident dentist did not arrive until 1943, while the local hospital was not established until 1944. Oppenheimer later recalled, “The notion of disappearing into the desert for an indeterminate period and under quasi-military auspices disturbed a good many scientists and the families of many more.” As Richard Rhodes explains in his book The Making of the Atomic Bomb, “The hardships only mattered because they slowed the work. Oppenheimer had sold [the Los Alamos assignment] as work that would end the war to end all wars and his people believed him.”

Los Alamos was a place cloaked in anonymity. No one could use the word “physicist,” and everyone was known as an “engineer.” Famous scientists were given pseudonyms. Niels Bohr, for example, was known as “Nicholas Baker,” and Enrico Fermi as “Henry Farmer.” During the entire war, all incoming mail was addressed simply to “P.O. Box 1663, Santa Fe, New Mexico.”

In this austere setting, the scientific team at Los Alamos set out to design the atomic bomb. The theoretical basis of building a bomb was already understood, but much of the technological work remained. The problem was how to build a bomb that would get its explosive energy from the fusion of either uranium 235 or plutonium 239. To do this, the scientists had to prepare two fissionable core materials. So in 1943 the government began building a separation plant at Oak Ridge, Tennessee. The project took two years to complete. Plutonium gradually became available in small amounts varying from micrograms to grams. By late 1943, the government had decided that the only way it could evaluate the results of an atomic bomb explosion was to test the one being constructed. Too much was still unknown about the weapon. So the government launched what became known as Project Trinity.

Testing the Bomb

On September 7, 1944, the committee chose a site near Los Alamos to test the bomb, known as the Jornada del Muerto (journey of death). Bleak and isolated, Jornada, a part of the Alamorgordo Bombing Range, was located about two hundred miles from Los Alamos. The closest inhabitant lived twelve miles away.

Before the actual bomb was exploded, and to prepare for the real test, the scientists scheduled a smaller, trial explosion using one hundred tons of TNT and one hundred curies of fission products for May 5, 1945. The date eventually had to be changed to May 7 so additional equipment could be installed. The trial run, when it finally took place, was itself spectacular. The orange fireball generated by the blast was seen as far away as the Alamorgordo base ten miles away. Kenneth Bainbridge, Trinity’s project director, commented, “No one who saw it could forget it, a foul and awesome display.”

Nevertheless, scientists working on the project, including Oppenheimer himself, wondered if the real bomb would work. So many questions still remained unanswered, including the big one: Had anything been overlooked?

In the months following the trial run, plans for the final test proceeded. Observation planes made passes over the test site to simulate the dropping of the bomb. Plutonium was stockpiled. Meanwhile, high-ranking observers began to assemble in New Mexico, including William L. Laurence of The New York Times, the sole reporter allowed to document the atomic bomb’s development.

The big date for the test was July 16, 1945. General T. F. Farrel, an observer, described the mood as the countdown continued: “The scene inside the shelter was dramatic beyond words. It can be safely said that most everyone present was praying. Oppenheimer grew tenser as the seconds ticked off. He scarcely breathed. He held on to the post to steady himself.”

Then at 5:29:45 a.m. Mountain War Time, the bomb exploded, creating a brilliant burst of light and a multicolored cloud that pushed and billowed upward. The light illuminated the landscape. The spectacle was seen in Santa Fe as well as Albuquerque and El Paso. One man thirty miles away in Carrizozo recalled, “It sure rocked the ground. You’d have thought it went right off in your backyard.”

It would be weeks before the measurements taken of the test would be corroborated and interpreted, but it was immediately apparent that the test was a success. The Allies now had the power to crush Japan and end the war.

Three weeks after the Trinity test, on August 6, the crew of the bomber Enola Gay dropped an atomic bomb on the Japanese city of Hiroshima. Three days later, another Trinity-type bomb exploded near another Japanese city, Nagasaki. Within days, the conflict with Japan had ended. World War II was over, the Cold War was about to begin.

Today at Los Alamos a community has grown around the laboratory where the atomic bomb was built. That laboratory is still operated by the University of California under contract with the Atomic Energy Commission for research in atomic energy.

For Further Information
  • Purcell, John. The Best Kept Secret: The Story of the Atomic Bomb. New York: Wingard Press, 1963. An early but still reliable work.
  • Rhodes, Richard. The Making of the Atomic Bomb. New York: Simon & Schuster, 1986. Perhaps the most thorough and reliable book about Los Alamos.
  • Rothman, Hal. On Rims and Ridges: The Los Alamos Area Since 1980. Lincoln: University of Nebraska Press, 1992. Puts the Los Alamos laboratory in historical context.
  • Schroyer, Jo Ann. Secret Mesa: Inside Los Alamos National Laboratory. New York: John Wiley & Sons, 1998. The history of the laboratory and early nuclear weapons research.
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