Manhattan Project National Historical Park

Manhattan Project National Historical Park Learn about the people, stories, and legacies of a top-secret project that forever changed the world.

Learn about the people, events, science, engineering and legacies of the Manhattan Project. The top-secret project ushered in the nuclear age with the development of the world’s first atomic bombs. The building of atomic weapons began in 1942 in Hanford, WA; Los Alamos, NM; and Oak Ridge, TN. As World War II waned in 1945, the United States dropped the atomic bombs on Hiroshima and Nagasaki, Japan — forever changing the world.

06/18/2026

Due to inclement weather in Oak Ridge, tonight’s Tennis Court Dance is cancelled. Join the park for the next Tennis Court Dance on Thursday, July 16 at 7pm ET.

In 1942 during the search for a location for Project Y, Oppenheimer wanted it to be somewhere unique. He felt this was i...
06/18/2026

In 1942 during the search for a location for Project Y, Oppenheimer wanted it to be somewhere unique. He felt this was important since everyone would be behind barbed wire fences, living in spartan accommodations, far from family and friends, and working hard six days a week.

They chose Los Alamos, which provided lots of opportunities for outdoor recreation. Civilian families who had cars made sure to fill any empty seats with young Army people, so they could get out too. One Sunday Genia Peierls and Bernice Brode gathered up some of the bachelor scientists and three Navy ensigns to drive to Bandelier National Monument for a hike to the Stone Lions, an ancestral Pueblo shrine. The trail was six and a half strenuous, sun-drenched miles each way, including crossing several steep-walled canyons. When they returned to the cars, hot, thirsty, and footsore, one of the scientists “spoke in his soft voice with a slight German accent, ‘I have not seen New York, nor Chicago¸ but I have seen the Stone Lions.’ “ It was Klaus Fuchs, and he would later also see the inside of a British prison - when he was convicted of being a spy. Families with children often chose the easier trip, driving into Frijoles Canyon to have picnics along the shady creek. The park was closed to the public during the war, so while the children played in the water, scientist fathers could walk up the canyon and discuss project questions without being overheard by other visitors. In fact, it was a given that when members of the project were mountain climbing, or fishing, or gathering mushrooms, or other outdoor activities, they would inevitably be engrossed in work discussions.

Image Credit: NPS

Join Manhattan Project National Historical Park, in partnership with Oak Ridge Associated Universities (ORAU) in explori...
06/17/2026

Join Manhattan Project National Historical Park, in partnership with Oak Ridge Associated Universities (ORAU) in exploring the peaceful uses of the atom. Utilizing the rich history and museum collection of the ORAU Museum of Radiation and Radioactivity, this program will dive into atomic culture and innovations in medicine sparked by the Manhattan Project and expanded during the atomic age. Participants will have the unique opportunity to explore the Museum of Radiation and Radioactivity, not regularly open to the public.

This free and accessible program will take place at ORAU's Pollard Center on Tuesday, June 23 at 2pm EDT. For more information: https://www.nps.gov/planyourvisit/event-details.htm?id=4F6C8B24-0A8D-046F-7AEA6B1E7B68C9E7

Image Credit: Oak Ridge Associated Universities

Across the World War II home front, industrial centers and port cities experienced phenomenal growth. Americans flocked ...
06/15/2026

Across the World War II home front, industrial centers and port cities experienced phenomenal growth. Americans flocked to these “boom towns” looking for good paying jobs that supported the fighting in Europe and the Pacific. With the employment needs of the project vastly exceeding US Army estimates, Manhattan Project administrators faced housing shortages at all sites. In Los Alamos, nearly any school building or homesteader cabin was fair game to house workers. Oak Ridge, the largest city of the project, faced an acute housing need as workers rushed to build homes for the 75,000 workers and dependents to reside in the town by 1945.

Throughout Oak Ridge, housing varied from extremely temporary (plywood hutments) to semimobile (trailers and modular homes), to more permanent but still quickly constructed single-family homes (the Alphabet Houses). The Alphabet Houses were also known as "cemestos", referencing the buildings’ cement and asbestos panels. Alphabet Houses, only available to higher-grade White workers, came in eight types, A through H, with larger home types generally later in the alphabet. Throughout the northern residential neighborhoods of Oak Ridge, these homes are still plentiful and actively lived in.

Image Caption: A Type B-1 Flat Top house, one of many designs in Oak Ridge during the Manhattan Project.

Image Credit: US Department of Energy/Ed Westcott

Put on your dancing shoes, another season of Tennis Court Dances is in full swing at the Jackson Square Tennis Courts. H...
06/14/2026

Put on your dancing shoes, another season of Tennis Court Dances is in full swing at the Jackson Square Tennis Courts. Held monthly on the third Thursday, Manhattan Project National Historical Park recreates the open-air tennis court dances held in Oak Ridge during the Manhattan Project to entertain the 75,000 war workers and their families contained within America’s Secret City.

For more information on this free and accessible program, please visit: https://www.nps.gov/planyourvisit/event-details.htm?id=3CE60324-B09B-E05D-8E922DE8E7B9319C

Image Credit: US Department of Energy/Ed Westcott

Wartime Oak Ridge was sustained by a flow of commuters, the majority of whom passed over the Solway and Edgemoor Bridges...
06/11/2026

Wartime Oak Ridge was sustained by a flow of commuters, the majority of whom passed over the Solway and Edgemoor Bridges. Built by Knox and Anderson Counties, these bridges predate World War II and were controlled by the Manhattan Project when the fence was built around Oak Ridge. In 1943, under pressure from Tennessee Governor William Cooper, the Army agreed to pay Knox County $25,000 annually ($450,000 in 2024 dollars) for use of Solway Bridge and maintenance of the Oak Ridge approach roads in Knox County.

By early 1944, heavy traffic into Oak Ridge had damaged the roads reducing the speed limit approaching the bridge to only 10 miles per hour. With heavy spring rains, the road washed out in February 1944. With no way to compel Anderson County to make repairs, Oak Ridge contractors began maintaining over 45 miles of Knox County roads.

Image Caption: The Solway Bridge pictured in 1943.

Image Credit: US Department of Energy/Ed Westcott

At the onset of the Manhattan Project, leadership became concerned with recruiting and retraining young scientists and e...
06/09/2026

At the onset of the Manhattan Project, leadership became concerned with recruiting and retraining young scientists and engineers, especially as draft regulations became increasingly strenuous. On May 22, 1943, the Army established a Special Engineer Detachment (SED). The first SEDs arrived in Oak Ridge by late July, followed shortly with a company in Los Alamos by August 1943. By the end of the war, Los Alamos would employ over 1800 SEDs and Oak Ridge had over 1200.

A SED, Val Fitch, later remembered this from his time in Los Alamos, “We lived in single floor barracks, roughly 60 men to a unit… We ate in an army mess hall… We lined up each week to get fresh linen, and once a month to get paid. Reveille came at 6 am, and we had calisthenics from 6:30 to 7:00. We could not leave the barracks for work on Saturday mornings until after inspection of quarters, nominally at 8:00. We worked in… the Tech Area six days a week. It was the army and still it wasn't the army because in the Tech Area we worked alongside, and were beholden to, civilians.”

Image Credit: US Department of Energy/Ed Westcott

🚴‍♂️ Ride with a Ranger — June 13!Get your tickets while they last!Register today for Ride with a Ranger on Saturday, Ju...
06/08/2026

🚴‍♂️ Ride with a Ranger — June 13!
Get your tickets while they last!

Register today for Ride with a Ranger on Saturday, June 13, from 9:00 am to 12:00 pm (PDT) in Richland, WA!
Join us for a 17-mile round trip bike ride along the along the Sacagawea Heritage Trail, on city streets through the Richland Parkway, and then continuing along the river to the REACH Museum.

We'll depart from the tennis courts in Leslie Groves Park and make our way to the REACH, where participants can enjoy:
• Hands on activities
• Programs about the Manhattan Project and local plants and animals
• Museum exhibits
Afterward, ride back to Leslie Groves Park with the rangers or on your own.

⭐ This event is FREE, but registration is required.
Registration is open now and closes on June 11 at 6:00 pm.
Thanks to Bike Tri Cities, museum admission is covered for all registered participants!
👉 Learn more and register: https://www.biketricities.org/event-6664724

Image Credit: NPS/REACH Museum

On this day 82 years ago, 6939 allied vessels comprising the largest amphibious invasion in history approached the coast...
06/06/2026

On this day 82 years ago, 6939 allied vessels comprising the largest amphibious invasion in history approached the coast of Normandy, France. Over 150,000 allied soldiers landed on the beaches that morning in an effort to open a second front against N**i Germany and hasten the end of World War II.

The evening prior, US General Dwight D. Eisenhower, commander of the Allied Expeditionary Force, released the following message to the troops:

"Soldiers, Sailors, and Airmen of the Allied Expeditionary Force!
You are about to embark upon the Great Crusade, toward which we have striven these many months. The eyes of the world are upon you. The hope and prayers of liberty-loving people everywhere march with you. In company with our brave Allies and brothers-in-arms on other Fronts, you will bring about the destruction of the German war machine, the elimination of N**i tyranny over the oppressed peoples of Europe, and security for ourselves in a free world.

Your task will not be an easy one. Your enemy is well trained, well equipped and battle-hardened. He will fight savagely.

But this is the year 1944! Much has happened since the N**i triumphs of 1940-41. The United Nations have inflicted upon the Germans great defeats, in open battle, man-to-man. Our air offensive has seriously reduced their strength in the air and their capacity to wage war on the ground. Our Home Fronts have given us an overwhelming superiority in weapons and munitions of war, and placed at our disposal great reserves of trained fighting men. The tide has turned! The free men of the world are marching together to Victory! I have full confidence in your courage, devotion to duty and skill in battle. We will accept nothing less than full Victory!

Good luck! And let us beseech the blessing of Almighty God upon this great and noble undertaking."

Image Caption: General Dwight D. Eisenhower speaking to paratroopers shortly before D-Day.
Image Credit: US National Archives & Records Administration

Beginning construction in Oak Ridge in June 1943, the K-25 Gaseous Diffusion Plant, with its distinctive U shape, was th...
06/02/2026

Beginning construction in Oak Ridge in June 1943, the K-25 Gaseous Diffusion Plant, with its distinctive U shape, was the largest building in the world during the Manhattan Project. Covering a 44-acre tract over one-half mile long and 1,000 feet wide, this top-secret facility employed over 10,000 workers at its height of operation in 1945.

The K-25 Gaseous Diffusion Plant, along with two other nearby massive Manhattan Project facilities, the Y-12 Electromagnetic Isotope Separation Plant and the S-50 Liquid Thermal Diffusion Plant, operated with the intent of enriching or separating lighter uranium-235 from heavier uranium-238.

Unlike the processes used at Y-12 and S-50, K-25 relied on over 3,000 gaseous diffusion steps through which uranium hexafluoride gas could pass through. This process allowed for smaller uranium-235 atoms to pass through the tiny pores in the barriers of each step, enriching the gas and creating a higher concentration of uranium-235. This gaseous diffusion method proved cheaper and more efficient than Y-12's electromagnetic separation process and S-50's liquid thermal diffusion process. Uranium-235 enriched at S-50, K-25, and Y-12 was used in Little Boy, the atomic bomb dropped on Hiroshima, Japan on August 6th, 1945.

The K-25 complex produced enriched uranium for defense and commercial purposes until the mid 1980s. Its benchmark gaseous diffusion method was the only uranium enrichment method used by the United States during the Cold War. In 2013, due to its deteriorated condition, Department of Energy contractors demolished K-25.

Image Credit: US Department of Energy/Ed Westcott

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Hanford, Washington; Los Alamos, New Mexico; Oak Ridge
Oak Ridge, TN

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