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July 2020

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U.S. Census Bureau History: The Manhattan Project

Trinity Test Site

On December 28, 1942, President Franklin D. Roosevelt authorized the "Manhattan Project"
with the goal of weaponizing nuclear energy. Under the direction of nuclear physicist
J. Robert Oppenheimer and Lieutenant General Leslie R. Groves, thousands of people
worked under strict secrecy at sites throughout the United States.

On July 16, 1945, years of research and design culminated in the detonation of the
worlds first atomic bomb northwest of Alamogordo, NM. Two months later, Groves
and Oppenheimer returned to the site (above) for photographs.

Photo courtesy of the Library of Congress.

Seventy-five years ago this month, scientists led by civilian physicist J. Robert Oppenheimer and Lieutenant General Leslie R. Groves successfully tested a weaponized release of atomic energy in the New Mexican desert. The July 16, 1945, blast known as the "Trinity Test" was the culmination of years of research conducted at sites throughout the United States as part of the Manhattan Project. The test—which produced a 22 kiloton blast—changed the course of World War II and the future of international relations.

Atomic research was underway at a number of universities in the United States in the late 1930s, including studies led by Ernest Lawrence at the University of California at Berkeley's Radiation Laboratory. Enrico Fermi and Leo Szilard also led studies at Columbia University and later the University of Chicago. Encouraged by these teams' research, President Franklin D. Roosevelt approved establishment of the Manhattan Engineer District—"The Manhattan Project"—on August 13, 1942, naming Lieutenant General Leslie R. Groves to oversee research into weaponizing atomic energy.

In October 1942, Groves selected University of California at Berkeley physicist J. Robert Oppenheimer to lead weapons research, and Oppenheimer chose a site near Los Alamos, NM, to conduct his work. On December 2, 1942, Enrico Fermi's University of Chicago team successfully initiated the world's first, self-sustaining chain reaction. Encouraged by this major development in atomic research, President Franklin D. Roosevelt approved funding for The Manhattan Project's research

Groves and Oppenheimer quickly began moving staff to sites throughout the United States including the primary research facility at Los Alamos, NM, and uranium processing installations in Benton County, WA; and Oak Ridge, TN, along with numerous smaller supporting facilities like those in Ames, IA; Morgantown, WV; and Sylacauga, AL. By early 1944, the scientists had successfully developed the infrastructure necessary to sustain the nation's atomic weapons program and produced designs for uranium- and plutonium-fueled bombs by mid-1945.

On July 13, 1945, the Manhattan Project scientists began assembling the plutonium bomb—nicknamed "The Gadget"—in a remote area of New Mexico's Socorro County, chosen as the site for the "Trinity Test." Upon completion, it was hoisted to the top of a 100-foot steel tower and armed late in the evening of July 15. As American B-29s circled overhead and scientists and military personnel observed from the ground, the device exploded at 5:29 a.m., releasing energy equivalent to 22 kilotons of TNT. The heat from the blast melted the nearby sand into glass and according to an eyewitness account, "the whole country was lighted by a searing light with the intensity many times that of the midday sun." A mushroom cloud of radioactive smoke and debris rose more than 7 miles into the atmosphere and people reported feeling and hearing the blast more than 100 miles away. Years later, Oppenheimer recalled that a line from the Hindu scripture Bhagavad Gita came to mind upon witnessing the atomic blast: "Now I am become Death, the destroyer of worlds."

President Harry S. Truman authorized use of the untested uranium bomb ("Little Boy") and plutonium bomb ("Fat Man") on Japan in late July 1945. On July 25, Acting Army Chief of Staff Thomas Handy ordered Commanding General Carl Spaatz of the Army Air Force's 509th Composite Group to target the Japanese cities of Hiroshima, Kokura, Niigata, and Nagasaki, Japan with atomic weapons. On August 6, 1945, a B-29 bomber named Enola Gay left its base on the Pacific island of Tinian (Commonwealth of Northern Mariana Islands) for Hiroshima, Japan, carrying the 9,700 pound "Little Boy" uranium bomb. The bomb detonated 1,900 feet above the city at 8:15 a.m. local time. On August 9, the plutonium bomb "Fat Man" carried by a B-29 named Bock's Car exploded above Nagasaki, Japan. Japan offered to surrender to the Allies the next day, and General Douglas MacArthur formally accepted Japan's unconditional surrender aboard the USS Missouri on September 2, 1945.

You can learn more about the Manhattan Project and Trinity Test using census data and records. For example:

  • Research to weaponize atomic energy as part of the Manhattan Project took place throughout the United States and populations near these atomic research and development installations grew as the United States added to its nuclear arsenal during the Cold War. For example, between the 1940s and 1960, Oak Ridge, TN, (home to the Oak Ridge National Laboratory) grew from a few thousand residents to 27,169. Similarly, the population of Los Alamos, NM, (site of the Los Alamos National Laboratory) grew from a few homesteads prior to World War II to 11,310 in 1970. The growing demand for nuclear fuel from the Hanford Nuclear Reservation led the population of Benton County, WA, to grow from 12,053 in 1940 to 51,370 in 1950. In 2010, the population of Oak Ridge, TN, was 29,330. The population of Los Alamos, NM, was 12,019; and although the Hanford Nuclear Reservation is no longer active, 175,177 still called Benton County, WA, home.
  • In August 1939—3 years before President Franklin D. Roosevelt authorized the Manhattan Project—Leo Szilard, Edward Teller, Albert Einstein, and other prominent physicists sent the president a letter warning him of Nazi Germany's atomic research and urged the president to fund an American research program. Roosevelt authorized the creation of the Advisory Committee on Uranium, which funded the purchase of uranium and graphite for experimentation in late 1939. On December 2, 1942, a team of scientists led by Enrico Fermi succeeded in producing the first controlled, self-sustaining nuclear chain reaction Link to a non-federal Web site in a reactor at the University of Chicago. Later that same month, Roosevelt authorized the Manhattan Project with the goal of weaponizing atomic energy.
  • In the decades since scientists weaponized atomic energy, the power unleashed by splitting atoms has found a more peaceful application through the generation of electricity. President Dwight D. Eisenhower commissioned the nation's first commercial nuclear power plant—the Shippingport Atomic Power Station—in Shippingport, Beaver County, PA, on May 26, 1958. By 2017, the U.S. Census Bureau's County Business Patterns Survey reported there were 178 nuclear electric power generation establishments (NAICS 22113) in the United States employing nearly 48,000 people. North and South Carolina led the nation for the number of nuclear power generating establishments with 32 and 25 establishments, respectively.
  • Thirteen years after the Manhattan Project's July 1945 Trinity Test, the world's first nuclear-powered submarine—the USS Nautilus (SSN-571)—completed the first-ever submerged transit of the geographic North Pole on August 3, 1958. Learn more about the USS Nautilus and other historic submarines at our History Web page commemorating the 60th anniversary of Nautilus' polar journey.
  • The United States was the only nation possessing atomic weapons until the Soviet Union successfully detonated a 22-kiloton bomb in Kazakhstan on August 29, 1949. Top secret documents provided by American citizens Julius and Ethel Rosenberg were key to the Soviet's nuclear weapons program. According to Soviet leader Nikita Khrushchev, the Rosenbergs "provided very significant help in accelerating the production of our atomic bomb." The couple was convicted of espionage on March 29, 1951, and executed at the Sing Sing Correctional Facility in Ossining, NY, on June 19, 1953. Over the next 60 years, nuclear weapons proliferated as Great Britain, France, China, India, Pakistan, and North Korea tested their own atomic weapons.
  • The heavy metal uranium was key to the development of the United States' first atomic weapon. When an uranium atom splits, it releases heat. A fission chain reaction is achieved when splitting atoms cause other atoms to split. Multiplied millions of times, the reaction releases an enormous amount of heat from a small amount of uranium. Today the highest concentrations of Uranium are found in the western and southwestern United States. The 2017 Economic Census reported that 18 establishments were involved in the mining of uranium, radium, and vanadium ore (NAICS 212291) in the United States employing 475 employees.
  • According to the U.S. Department of Labor, there were 16,730 physicists employed in the United States earning a mean annual wage of $123,080 in May 2019. California (1,950), Maryland (1,880) and New Mexico (1,740) led the nation for the number of physicists employed. Many of these physicists are federal employees. They work at agencies including the National Aeronautic and Space Administration which employs astrophysicists; the U.S. Nuclear Regulatory Commission which employs nuclear physicists to regulate the civilian use of nuclear power and materials; and the U.S. Department of Energy which employs and awards grants to physicists to perform research at facilities, including Oak Ridge National Laboratory in Oak Ridge, TN; Argonne National Laboratory in Lemont, IL; Lawrence Livermore National Laboratory in Livermore, CA; Los Alamos National Laboratory in Los Alamos, NM; and Sandia National Laboratories in Albuquerque, NM, and Livermore, CA.

Manhattan Project Trinity Test

After years of research, the Manhattan Project successfully detonated the world's first nuclear device at 5:29 a.m., on July 16, 1945. Conducted 75 miles northwest
of Alamogordo, NM, the Trinity Test released between 18 and 22 kilotons of explosive energy proving that atomic energy could be weaponized.

The U.S. Army erected a monument at the detonation site in 1965. On December 21, 1965, The U.S. National Parks Service declared the Trinity Test Site and more
than 50,000 acres surrounding the site—now part of the White Sands Missile Range—a National Historic Landmark district. On October 15, 1966, it was listed
on the National Register of Historic Places.

Image courtesy of the National Parks Service.

Atomic Occupations

In 2017, the American Community Survey estimated that the United States was home to 5,930 nuclear engineers and 3,361 nuclear technicians.

In addition to academic pursuits, many of these professionals work at nuclear electric power generation facilities (NAICS 221113); pharmaceutical manufacturers specializing in radiology and nuclear medicine (NAICS 325412); and naval ship building and repairing (NAICS 336611).

Albert Einstein
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Physicist Albert Einstein (shown above participating in the 1950 Census) and his wife immigrated to the United States in 1933 and settled in Princeton, NJ. He became a permanent resident while working at the Institute for Advanced Study Link to a non-federal Web site in 1935, and an American citizen in 1940.

Despite being one of the world's premier physicists, Einstein's pacifism and socialist beliefs led President Franklin D. Roosevelt's administration to prohibit Einstein from participating in the Manhattan Project. Instead, Einstein lent his expertise to the U.S. Navy by evaluating weapons systems and raising money for the war effort.

Use census data and records to learn more about Einstein and his research at our March 2019 Web page commemorating the physicist's 140th birthday.

Census employees in 1910
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This Month in Census History

Prior to 1902, the U.S. Census Bureau was a temporary agency opened to conduct the census and closed when staff completed publishing data each decade.

On March 6, 1902, Congress enacted legislation creating the permanent Census Bureau. The agency officially opened its doors as part of the Department of the Interior on July 1, 1902.

The Census Bureau moved to the newly created Department of Commerce and Labor in 1903, and remained within the Department of Commerce following the creation of separate Departments of Commerce and Labor in 1913.

Today, the Census Bureau is headquartered in Suitland, MD. It remains part of the Department of Commerce under the leadership of Secretary Wilbur L. Ross, Jr. and agency director Dr. Steve Dillingham.

Visit https://www.census.gov/history every month for the latest Census History Home Page!

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Source: U.S. Census Bureau | Census History Staff | Last Revised: December 14, 2020