The Manhattan Project operated at three key sites, each with a distinct role in building the first atomic bomb.

The Manhattan Project, the top-secret American program that built the world's first atomic bomb, cost $27B in today's dollars and reshaped global power.

Building the first atomic bomb required unprecedented coordination

Creating the first atomic bombs demanded breakthroughs in physics, engineering, and logistics—uniting elite scientists with tens of thousands of workers across the US. This in-depth history explains how the Manhattan Project overcame those challenges.

The Manhattan Project was one of the most expensive undertakings of World War II

Building the first atomic weapons required hundreds of thousands of workers, vast secret facilities, and enormous spending. This 1998 study details the full cost of the Manhattan Project and compares it to other major US wartime expenditures.

Interviews from the Manhattan Project

This is an archive of interviews with people who worked on and were impacted by the Manhattan Project, the World War II-era effort that resulted in the atomic bomb. Listen to the "father of the atomic bomb," Julius Robert Oppenheimer, describe his daily routine during the project, which he reports officially started Dec. 6, 1941. This archive also includes interviews with survivors of the Hiroshima and Nagasaki bombings.

Robert Oppenheimer became the face of the Manhattan Project and the atomic bomb

This feature explores Oppenheimer’s early life, the traits that made him central to the development of the atomic bomb, and how his later years were marked by tension between pride in his work and opposition to weapons of mass destruction.

The story of the Manhattan Project's unused demon core

A 3-inch, 14-pound sphere of nuclear reactive plutonium-gallium was set to be delivered to the Pacific Theater in 1945 to become the third atomic bomb dropped over Japan. When Japan surrendered, it was returned to Los Alamos in New Mexico for experiment, where two scientists would die testing whether the core could reach criticality—where it would release intense energy—via the use of a dense reflector. Watch the story here.

The Manhattan Project created secret cities that didn’t appear on maps

To maintain secrecy, the US built three remote research facilities and entire “secret cities” to house thousands of workers and families. These communities—home to tens of thousands—were omitted from official maps until after World War II.

Spies working on the Manhattan Project propelled the Soviet bomb program

Soviet infiltration—most notably by Klaus Fuchs—smuggled detailed implosion-design and hydrogen‑bomb data from Los Alamos to Moscow, cutting the USSR’s development time by at least a year and enabling their first atomic test in August 1949.

Meet the scientists who worked on the Manhattan Project.

Oppenheimer reflected on the atomic bomb's legacy two decades later

In a 1965 CBS interview, J. Robert Oppenheimer discussed his role as Los Alamos director, expressing deeply mixed feelings about Hiroshima and Nagasaki and reflecting on how nuclear weapons had transformed the world since their first use.

A four-part podcast traces how the Manhattan Project reshaped the world

This podcast series explores the origins of the Manhattan Project, its secret cities, and the scientists behind it—showing how the effort contributed to the end of World War II, launched the Atomic Age, and later led Oppenheimer to become a critic of nuclear weapons.

Explore the components of the linear particle accelerator at Los Alamos

Located at the site of bomb design and development for the Manhattan Project, LANSCE features an injector system for hydrogen ions, a series of tanks with alternating electric fields for proton acceleration, and an isotope production facility that creates radioisotopes for medical treatments.

On August 6, 1945, the Enola Gay dropped the first atomic bomb used in warfare on Hiroshima, Japan, killing at least 80,000 people instantly.

The first nuclear reactor was built three years after nuclear fission was discovered

After learning that large atomic nuclei release energy upon being split apart, scientists quickly researched how to control the reaction to make electricity. Fusion—combining small atomic nuclei—generates massive energy in stars and hydrogen bombs.

The Soviet Union’s surprising first atomic test ended the US nuclear monopoly

In 1949, the USSR successfully tested its first atomic bomb—ending the US monopoly on nuclear weapons and sparking an arms race that would define the Cold War.

While both are nuclear weapons, atomic bombs release nuclear energy by splitting large atomic nuclei, whereas hydrogen bombs derive most of their energy from fusing heavy hydrogen isotopes.

The H-bomb is hundreds of times more powerful than the bomb dropped on Hiroshima

Unlike the atomic bombs dropped on Hiroshima, which relied on nuclear fission, the hydrogen bomb uses fusion to unleash vastly greater destructive power. Developed by both superpowers in the 1950s, it gave each the ability to destroy entire cities in seconds.

Modern Marvels examines the Manhattan Project

This episode of the television program 'Modern Marvels' focuses on the Manhattan Project, combining archival footage and interviews with historians and scientists to shed light on one of the most ambitious military and scientific endeavors in human history.

Cold War nuclear tests exposed thousands to atomic blasts

After World War II, nuclear powers conducted thousands of weapons tests. This video pairs archival footage with interviews of veterans who witnessed Pacific test explosions, capturing the scale, shock, and human experience of being near a nuclear detonation.

The Gasbuggy Project detonated a nuclear bomb to fracture underground rock formations

Part of Project Plowshare—a program aimed at finding peaceful uses for nuclear devices—the 1967 experiment sought to extract natural gas trapped within shale in underground New Mexico. Gas radioactivity was found to be excessively high for use without expensive processing, and the project was deemed an economic failure.

In 1962, the US detonated a nuclear weapon in space, which produced an electromagnetic pulse that disabled three low Earth orbit satellites and damaged electrical equipment in Hawaii.

The origin of atmospheric science while testing nuclear weapons during the Cold War

The arms race between the US and the Soviet Union saw both countries stockpiling and detonating hundreds of bombs underground, underwater, and in the atmosphere. To better predict where nuclear fallout would travel after these tests, scientists developed models that would serve as a foundation for those used to explain atmospheric circulation.

Worried that Nazi Germany could weaponize nuclear fission first, Albert Einstein wrote a 1939 letter warning President Roosevelt about the possibility of atomic bombs—a decision he later regretted.

Before 1932, when particle accelerators were first used for nuclear research, scientists relied on naturally radioactive substances to advance their understanding of the atomic nucleus.

Penicillin production was just behind the atom bomb in wartime priorities

By 1943, the US War Department made penicillin its second-highest priority—just after the Manhattan Project. Producing enough of the antibiotic for the D-Day invasion became a central mission of Allied science and industry.

During the Cold War, a mid-air fire led to a nuclear bomber crash in Greenland that left a piece of a hydrogen bomb missing to this day.

See where the 94 nuclear reactors in the continental US are located

In 2023, these reactors—located in 53 plants across 28 states—prevented 437 million tons of carbon dioxide emissions. A single fingertip-sized uranium pellet generates as much electricity as a ton of coal, enough for one household's annual electricity.

The US once had a plan to nuke the moon

In the 1950s, the US considered detonating a hydrogen bomb on the moon as part of a Cold War show of force. Known as Project A119, the classified plan aimed to create a visible explosion from Earth to signal American dominance in the space race.

The US once had a plan to nuke the moon

In the 1950s, the US considered detonating a hydrogen bomb on the moon as part of a Cold War show of force. Known as Project A119, the classified plan aimed to create a visible explosion from Earth to signal American dominance in the Space Race.

The discovery of the neutron paved the way for nuclear weapons

In 1932, James Chadwick discovered the subatomic particle when trying to explain the radiation emitted by beryllium after it was bombarded with alpha particles. The radiation’s ability to eject protons from a target suggested a chargeless particle with slightly more mass than a proton.

J. Robert Oppenheimer’s grandson says his grandfather would back nuclear power

While the "father of the atomic bomb" referred to the bomb as "an evil thing," after the Manhattan Project, he also described nuclear energy’s potential as an environmentally friendly solution to address the world's energy problem.

The discovery of nuclear fission was facilitated by the discovery of the neutron

The discovery of the neutron provided scientists with a particle that could penetrate the nucleus and advance atomic physics. Otto Hahn was the sole Nobel recipient for the discovery of fission, despite collaborating with Lise Meitner and Fritz Strassmann.

US secrets: Project Paperclip

The US launched Project Paperclip in 1946, covertly recruiting over 1,500 German scientists to advance American military and space programs. Among them was Wernher von Braun, a key architect of the V-2 rocket who later became instrumental in NASA’s Apollo missions. While these scientists accelerated technological breakthroughs, their recruitment raised moral debates about overlooking wartime affiliations in the name of progress—questions that remain unresolved today.

For decades, the US has considered building a permanent nuclear waste repository

All nuclear waste would have been stored at Nevada's Yucca Mountain, but the Obama administration indefinitely stalled the project after intense community backlash. Spent fuel is now stored at more than 80 locations in 36 states, raising safety concerns.

Visualizing the chemistry of nuclear weapons

Nuclear weapons have devastating effects, but the science of how they work is atomically small. There are two main types of nuclear reaction: fission and fusion. The fission bomb produces immense energy by splitting an atom, the result of firing a...

The Bomb-proof, Cold War-era New York data center inspiring spy movies

At 33 Thomas Street in Lower Manhattan, New York City, a 45-story concrete tower with no windows stands imperiously over the city. Inside, 18 floors of telecommunications technology have hummed for decades. The building's purpose—to protect US comms from nuclear fallout—and its design have played into spy movie plotlines. Dive into the building's curious role in pop culture with this long read.

South Africa: the only nation to build nuclear weapons—and dismantle them by choice

During the 1980s, South Africa secretly built six uranium "gun‑type" nuclear bombs. In the 1990s, the government dismantled all its weapons and joined the NPT in 1991—the only country to fully reverse its nuclear program.

The atomic bombs dropped on Japan had massive human costs

The US atomic bombings of Hiroshima and Nagasaki in August 1945 killed around 210,000 people—more than 38,000 of them estimated to be children—with tens of thousands more later dying from radiation-linked illnesses, leaving lifelong trauma and increased cancer risks.

Ernest Rutherford's gold foil and nitrogen experiments revealed nuclear structure

Observing high-angle deflections when alpha particles were fired at gold foil led to an atomic model with a dense, positively charged nucleus. Firing those particles at nitrogen resulted in the emission of hydrogen nuclei—protons—leading to the discovery of the subatomic particle.

Hiroshimaites are glass-like spheres of fallout debris found in Hiroshima, where conditions created by the atomic bomb forged a previously unknown metal alloy with a unique crystal structure.

The oldest nuclear fission reactor on Earth formed naturally in West Africa about 2 billion years ago, where groundwater enabled atoms in uranium deposits to split, releasing energy.

Nine eyewitness accounts of Hiroshima and Nagasaki survivors

Japan's Hiroshima and Nagasaki became the first cities in history to be hit with nuclear weapons, where tens of thousands of civilians were killed nearly instantly. Hundreds of thousands of people who survived the bombings—referred to as hibakusha—dealt with wounds, radiation poisoning, and alienation from a society unable to process what had happened. This collection of accounts lets nine of those survivors speak, including one of the 165 survivors of both bombings.

Nuclear power relies on chain reactions involving uranium-235, but because the isotope's concentration in natural ores is too low to sustain these reactions, enrichment is needed to produce more highly concentrated fuel.

A US project proposed a 10-gigaton nuclear bomb capable of global devastation

Planned in the early 1950s by US scientists, Project Sundial aimed to create a 10-gigaton thermonuclear bomb—hundreds of times more powerful than any weapon ever built. Had it been tested, it was expected to cause global environmental catastrophe.

The death toll of the atomic bombings in Japan remains disputed, with estimates ranging from 110,000 to 210,000.

Okinawa’s ferocity convinced the US atomic bombs was necessary

The brutal 82-day Battle of Okinawa—where US forces suffered nearly 50,000 casualties and Japanese military and civilians lost over 200,000 lives—clinched the grim reality that a full invasion of Japan would be even bloodier. This stark lesson directly shaped American decisions to deploy atomic weapons, aiming to avoid a potentially catastrophic ground war on the Japanese mainland.

Uranium's ability to split easily makes it the most common catalyst for nuclear power

Uranium is commonly found in rocks, water, and soil worldwide, but significant industrial processes are needed to process and enrich it for efficient reactor usage. After being irradiated in reactors, it must be cooled down before disposal.

As of 2024, there are 90,000 tons of nuclear waste stored at 100+ sites in 39 states

Over 315,000 bundles of spent nuclear fuel rods are stored in water pools and over 3,800 dry storage casks in concrete vaults above ground. Corrosion from saltwater spray threatens waste containers of reactors near oceans.

Learn how Japan used the jet stream to launch attacks on US soil during World War II

In the final two years of the war, over 9,000 Fu-Go balloon bombs were launched from Japan, with about a thousand estimated to have reached North America. Six civilians killed by a Fu-Go bomb in Bly, Oregon, on May 5, 1945, became the only known deaths on American soil by enemy action during the war.

Simulations of atmospheric transport have shown that radioactive material released from potential strikes to US nuclear missile silos would reach everyone in the continental US.