Manhattan Project
National Historical Park
New Mexico-Tennessee-Washington
Park Photo
NPS photo


The Manhattan Project National Historical Park is one of the nation's newest national parks. Established in November 2015, the park preserves portions of the World War II-era sites where the United States developed the world's first atomic weapons. This unique park, managed in partnership by the National Park Service and the Department of Energy, will provide visitors the opportunity to walk in the footsteps of J. Robert Oppenheimer at Los Alamos, New Mexico; visit Hanford, Washington, to stand face to face with the nuclear reactor that produced the material for the first atomic test; and learn about the dedication of the Calutron Girls in Oak Ridge, Tennessee, who helped the United States win the race against Nazi Germany to develop an atomic bomb. The Manhattan Project and its legacy is a complex story. It's the story of more than 600,000 Americans leaving their homes and families to work on a project they were told was vital to the war effort. It's the story of generals, physicists, chemists, mathematicians, and engineers pushing and broadening the limits of human knowledge and technological achievement in ways never before imagined. It is also the story of the death and destruction associated with World War II, and a new weapon capable of unimagined levels of devastation. A visit to the Manhattan Project National Historical Park provides an opportunity to view the sites that helped the United States end World War II and challenges us to think about how the world has changed with the dawn of the nuclear age.


The Manhattan Project was an unprecedented, top-secret program implemented in the United States during World War II to design and build an atomic bomb. The discovery of nuclear fission in Germany suggested the possibility of a nuclear chain reaction with the potential release of enormous amounts of energy. Concerned, Leo Szilard prompted Albert Einstein in August 1939 to send a letter to President Franklin D. Roosevelt, warning that an "extremely powerful bomb" might be constructed. Fearing ongoing research and development by Nazi Germany, Roosevelt initiated federal funding for uranium research.

By 1942, with the United States at war, officials concluded that an atomic bomb could be designed, built, and used in time to influence the outcome of the war. To accomplish this task, the US Army Corps of Engineers established the Manhattan Engineer District, headed by Brigadier General Leslie Groves. This effort, combining military, scientific, and industrial resources and involving hundreds of thousands of workers at many sites across the country, was largely kept secret for the duration of the project.

Scientists theorized there were two potential paths to a bomb using uranium-235, which comprises about one percent of naturally occurring uranium, or the newly discovered element plutonium, which could be created from a controlled chain reaction with uranium. Both paths required the use of expensive and unproven processes and success was not guaranteed. As a result, the decision was made to move forward with both paths. For the uranium bomb, a massive industrial complex was built at Oak Ridge, Tennessee, to pursue the three separate technologies to enrich uranium at the same time. A pilot reactor and chemical separation plant were also constructed at Oak Ridge to test the plutonium production process. For full scale plutonium production, a second enormous industrial complex was built at Hanford, Washington. Workers built and operated huge reactors, chemical separations plants, and fuel fabrication and research facilities. Despite the speed with which the facilities were engineered and built, production at both sites was slow and difficult. It was not until mid-1945 that sufficient amounts of uranium-235 and plutonium were available for construction of the first bombs.

Building the bombs was not an easy task; it required extensive experimentation and precise calculations to obtain the optimum specifications. In early 1943, General Groves set up a bomb design and development laboratory, with some of the world's foremost scientists under the leadership of J. Robert Oppenheimer, at the isolated Los Alamos site in northern New Mexico. The uranium bomb used a fairly straightforward gun method for creating a critical mass and nuclear explosion. However, in 1944, scientists determined that the gun method would not work for plutonium, and they turned to the theoretical and complex implosion method. Uncertain it would work, a plutonium device was tested at the Trinity site in southern New Mexico on July 16, 1945.

As the project moved closer to the use of the first atomic bomb, ethical questions arose in the minds of some who understood the project's intent; however, scientists and politicians were primarily concerned with ending the war as quickly as possible. With Germany out of the war, the first uranium bomb was dropped on Hiroshima, Japan, on August 6, 1945. When Japan did not surrender, a plutonium bomb was dropped on Nagasaki, Japan, on August 9. On August 14, Japan announced its surrender and World War II ended.

The Manhattan Project is a highly significant chapter in United States history. It ushered in the nuclear age, determined how the next war, the Cold War, be fought, and served as the model for the remarkable achievements of American "big science" during the second half of the twentieth century. The Manhattan Project also raised ethical and moral questions among scientists and citizens alike—questions that continue to this day.

"The Atomic Age began at exactly 5:30 Mountain War Time on the morning of July 16, 1945, on a stretch of semi-desert land about 30 airline miles from Alamogordo, New Mexico. And just at that instance there rose from the bowels of the earth a light not of this world, the light of many suns in one."

—Journalist William L. Laurence, New York Times, September 26, 1945


Manhattan Project National Historical Park is a partnership park. The National Park Service is responsible for administration, interpretation, and education at the three sites and will provide technical assistance to resource preservation efforts. The Department of Energy will continue to have responsibility for management, operations, maintenance, and historic preservation of the historic Manhattan Project sites now under their jurisdiction. Other agencies, communities, organizations, and associated tribes may also become involved to tell the full story of the Manhattan Project.


A visit to the Manhattan Project National Historical Park will be different from a visit to many other national parks. Many of the properties included in the park are located in areas that are being cleaned up or are still active nuclear facilities. Because of safety and security concerns some facilities may not be immediately accessible and others may only accessible on organized bus tours. The National Park Service and the Department of Energy are working together to safely expand access to the facilities included in the park. We are also working with partners in local communities and from around the world to tell the complete story of the Manhattan Project and its legacy. Additional background on the Manhattan Project can be found at: To find out more about how to visit the park and what tours are available please visit:

"In answer to the question, 'Was the development of the atomic bomb by the United States necessary?' I reply unequivocally, 'Yes.' To the question, 'Is atomic energy a force for good or for evil?' I can only say, 'As mankind wills it.'"

—Brigadier General Leslie Groves


The Manhattan Project National Historical Park is composed of the three principal locations where work was completed as part of the Manhattan Project Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico. Each site performed a unique and critical role in the success of the project and today plays an important part in preserving the Manhattan Project story. The National Park Service plans to have a presence at all three of these locations.

Los Alamos, New Mexico
Located on a remote mesa in New Mexico, more than 6,000 scientists and support personnel worked to design and build the atomic bombs. The park currently includes three areas at Los Alamos. Gun Site, which includes three bunkered buildings (TA-8-1, TA-8-2, and TA-8-3), and a portable guard shack (TA-8-172). These buildings were associated with the design of the "Little Boy" bomb. Y-Site includes buildings TA-16-516 and TA-16-517, which were used by laboratory personnel to assemble components of the Trinity device in July 1945. Pajarito Site includes the Slotin Building (TA-18-1), the Battleship Bunker (TA-18-2), and the Pond Cabin (TA-4-8-29). Pajarito Site was used during the war for plutonium chemistry research and later became the main site for critical assembly work at Los Alamos after the war.

Oak Ridge, Tennessee
The Clinton Engineer Works, which became the Oak Ridge Reservation, was the administrative and military headquarters for the Manhattan Project and home to more than 75,000 people who built and operated the city and industrial complex in the hills of East Tennessee. The Oak Ridge Reservation included three parallel industrial processes for uranium enrichment and experimental plutonium production. At Oak Ridge, the park includes the X-10 Graphite Reactor National Historic Landmark, a pilot nuclear reactor which produced small quantities of plutonium; Buildings 9731 and 9204-3 at the Y-12 complex, home to the electromagnetic separation process for uranium enrichment; and the site of the K-25 Building, where gaseous diffusion uranium enrichment technology was pioneered. Buildings 9731, 9204-3 and K-25 together enriched a portion of the material for the uranium bomb.

Hanford, Washington
The Hanford Engineer Works was built to create large quantities of plutonium at a roughly 600-square-mile site along the Columbia River in Washington State. More than 51,000 workers at Hanford constructed and operated a massive industrial complex to fabricate, test, and irradiate uranium fuel and chemically separate out plutonium. The Hanford landscape is also representative of one of the first acts of the Manhattan Project, the condemnation of private property and eviction of homeowners and American Indian tribes to clear the way for the top-secret work. At Hanford the park includes: the B Reactor National Historic Landmark, which produced the material for the Trinity test and plutonium bomb; the Hanford High School in the Town of Hanford and Hanford Construction Camp Historic District; Bruggemann's Agricultural Warehouse Complex, White Bluffs Bank, and Hanford Irrigation District Pump House, which together provide a glimpse into the history of the Hanford area before the arrival of the Manhattan Project. The T Plant, a chemical separations canyon, will not be in the Park initially, but visitors will learn about its vital role at other locations in the park.

Source: NPS Brochure (undated)

Manhattan Project National Historical Park
Los Alamos, New Mexico

In 1943, the United States government's Manhattan Project built a secret laboratory at Los Alamos, New Mexico, for a single military purpose—to develop the world's first atomic weapons. The success of this unprecedented, top-secret government program forever changed the world.

In 2004, the U.S. Congress directed the National Park Service and the Department of Energy to determine the significance, suitability, and feasibility of including signature facilities in a national historical park. In 2014, the National Defense Authorization Act, signed by President Obama, authorized creation of the Park. This legislation stated the purpose of the park: "to improve the understanding of the Manhattan Project and the legacy of the Manhattan Project through interpretation of the historic resources." On November 10, 2015, a Memorandum of Agreement signed by the Secretary of the Interior and the Secretary of the Department of Energy made the park a reality.

Three locations comprise the park: Project Y at Los Alamos, New Mexico; Site X at Oak Ridge, Tennessee; and Site W at Hanford, Washington. The Manhattan Project National Historical Park legislation references 17 sites at Los Alamos National Laboratory, as well as 13 sites in downtown Los Alamos. These sites represent the world-changing history of the Manhattan Project at Los Alamos. Their preservation and interpretation will show visitors the scientific, social, political, and cultural stories of the men and women who ushered in the atomic age.

The properties below are within the Manhattan Project National Historical Park boundaries on land managed by the Department of Energy. These properties are not yet accessible to the public.


Originally built in 1914 by Mr. Ashley Pond as an office for the Pajarito Club, a private hunting ranch, the cabin was used by physicist Emilio Segre's group during the Manhattan Project to support plutonium chemistry research.


Built in 1944, this bunker supported implosion diagnostic tests for Fat Man. The Creutz implosion test was the final systems check of the gadget prior to the Trinity test. This building is known as a battleship building because the bunker's west end is bow shaped and shielded with a steel plate.


Constructed in 1946, this building supported criticality research. On May 21, 1946, a criticality accident occurred here during an experiment known as "tickling the dragon's tail." This accident led to the death of scientist Louis Slotin a few days later.

TA-8-1, TA-8-2, TA-8-3, & TA-8-172

During World War II, scientists at Gun Site conducted tests for the gun-assembled weapon designs known as Thin Man and Little Boy. Components of Little Boy were assembled here before shipment to the Pacific. Little Boy was deployed over Hiroshima on August 6, 1945.

TA-16-516 & TA-16-517

In 1944 this site supported the first assembly work related to the Fat Man weapon design. In July 1945, V-Site was also used to assemble the high-explosives sphere for the Trinity device, known as the gadget.

2016 Townsite Properties Walking Tour
Manhattan Project in the Los Alamos townsite

The Manhattan Project National Historical Park tells the story of the people, the events, and the science and engineering that led to the creation of the atomic bombs that helped bring an end to World War II. The park allows visitors to explore how the creation of these weapons changed the world and the United States' role in the world community. Additionally, the park addresses the subsequent controversy and contribution of the Project to the annals of history and the world in which we live.

Los Alamos, New Mexico, was where efforts of the Manhattan Project came together to discover the science needed to succeed, to invent the technical processes, and then to produce two devices and test them. In Los Alamos, the park experience is a partnership among the Department of Energy, the National Park Service, private landowners, and Los Alamos County.

Though the park was established in December 2015, full implementation will take time. In Los Alamos, the Department of Energy is developing phased access to its properties that are currently inaccessible. In the interim, visitors can see the properties on this walking tour of the townsite, visit the Bradbury Science Museum, the Historical Museum, and download the Manhattan Project virtual tour app.

Pick up your Park map, get one of the special three-part stamps in your passport, and download the Manhattan Project virtual tour app. The visitor contact station also serves as the temporary site of the Los Alamos Historical Museum.

Welcome to your tour of Project Y, the Manhattan Project's Los Alamos location.

This memorial contains original stone from the Ranch School's ice house, which was torn down in 1957. Project Y scientists used the ice house to assemble the nuclear components of the Trinity gadget, the first tested atomic device.

Ashley Pond is shown in the center of the fenced and guarded Technical Area 1 (TA-1). The pond was named after Mr. Ashley Pond, the founder of the Los Alamos Ranch School.

Sculptures of Dr. J. Robert Oppenheimer, scientific head of the Manhattan Project, and Gen. Leslie Groves, military head of the Project.

Fuller Lodge was built in 1928 as the dining hall for the Los Alamos Ranch School. During Project Y, the Lodge hosted community activities, such as concerts, dances, dinners, and other special events. Fuller Lodge continues this tradition to this day. Visitors are welcome.

Built as the infirmary for the Ranch School in 1918, this cottage is the oldest continuously used building in Los Alamos. It later served as a guest cottage for Ranch School visitors and was Gen. Leslie Groves' favorite place to stay in Los Alamos. The museum is being renovated; reopening in late 2016.

Built in 1925, this house briefly served during the Manhattan Project as the home of Sir James Chadwick, discoverer of the neutron in 1932, and later Robert Bacher, head of the Experimental Physics Division of the Project. Privately owned; no visitors, please.

This structure was built in 1933 to house the Ranch School's electrical generator. After remodeling it in 1944-1945, explosives expert George Kistiakowsky lived here. In 1950, the local Red Cross took it over as a chapter office.

This dormitory, for the older boys at the Ranch School, was converted into a Women's Army Corps dormitory at the beginning of Project Y. Eventually, it was divided into apartments, one of which was occupied by Kenneth Bainbridge, director of the Trinity test. Privately owned; no visitors, please.

Originally classrooms for the Ranch School, this building was divided into two apartments during the Manhattan Project. Among its residents were base commander Lt. Col. Whitney Ashbridge, a Ranch School graduate, and Norris Bradbury, second director of the Los Alamos Laboratory. Privately owned; no visitors, please.

Chemist Edwin McMillan and physicist Hans Bethe, both Nobel Prize winners, lived in this house. It will soon be a museum about the role Los Alamos played during the Cold War and the development of the community.

This house was built in 1929 for the sister of Ranch School Director A.J. Connell. Dr. J. Robert Oppenheimer and his family lived here during the Manhattan Project. Privately owned; no visitors, please.

Constructed in 1925, this house was originally occupied by Ranch School master Fermor Church and his wife, Peggy Pond Church, daughter of the school's founder. During Project Y, Naval Commander William "Deak" Parsons lived here. Parsons served as the weapons officer aboard the Enola Gay. Privately owned; no visitors, please.

This Manhattan Project dormitory housed some of the Women's Army Corps members stationed here. Now it is the privately-owned Christian Science Reading Room; no visitors, please.

This building was the favorite mess hall for the military members of the Project. Now it is the Los Alamos Performing Arts Center. Check for performance information.

Over 60 interactive exhibits trace the history of the Manhattan Project, highlight Los Alamos National Laboratory's defense and technology research projects, and focus on research addressing economic, environmental, political, and social concerns. You can also experience and download the Manhattan Project virtual tour app here.

Experience the Manhattan Project virtually. You can:
• Play an interactive game to complete training for clearance into increasingly more secret facilities;
• Get a bird's eye view of the Project with links to little-known facts; and
• Discover facts at waypoints along the Townsite Properties Walking Tour.

App available free at the Visitor Contact Station, the Bradbury Science Museum, and online in the Apple Store.

National Park website
Bradbury Science Museum website
Los Alamos Historical Society website
DOE Manhattan Project website

Source: NPS Brochure (undated)


Manhattan Project National Historical Park — Nov. 11, 2015

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Link to Official NPS Website

Brochures ◆ Site Bulletins ◆ Trading Cards expand section


A Brief History of the PUREX and UO3 Facilities (M.S. Gerber, November 1993)

African Americans at Los Alamos and Oak Ridge: A Historic Context Study (September 2019)

Construction, Hanford Engineering Works: History of the Project, Volume I (E. I. Du Pont de Nemours & Company, Inc., August 9, 1945)

Dramatic Change at T Plant (M.S. Gerber April 1994)

El Libro Para Guardaparques Juveniles, Manhattan Project National Historical Park - Oak Ridge (2016)

Foundation Document, Manhattan Project National Historical Park, Tennessee, New Mexico, Washington (January 2017)

Foundation Document Overview, Manhattan Project National Historical Park, Tennessee, New Mexico, Washington (January 2017)

Hanford Codes and Jargon (July 3, 1950)

History of the Plutonium Production Facilities at the Hanford Site Historic District, 1943-1990 (June 2002)

Junior Ranger Book (B Reactor), Manhattan Project National Historical Park - Hanford (Date Unknown)

Junior Ranger Book (Pre-Manhattan Project), Manhattan Project National Historical Park - Hanford (Date Unknown)

Junior Ranger Book, Manhattan Project National Historical Park - Los Alamos (2017)

Junior Ranger Book, Manhattan Project National Historical Park - Oak Ridge (2016)

Junior Ranger Book (Japanese), Manhattan Project National Historical Park - Oak Ridge (2016)

Key Documents (Atomic Heritage Foundation)

Manhattan Project Sites Special Resources Study — Washington Newsletter #1 (February 2006)

Manhattan Project Sites Special Resources Study — Tennessee Newsletter #2 (February 2006)

Manhattan Project Sites Special Resources Study — Ohio Newsletter #3 (February 2006)

Manhattan Project Sites Special Resources Study — New Mexico Newsletter #1 (May 2006)

Manhattan Project Sites Special Resources Study Newsletter #2 (September 2006)

Manhattan Project Sites Special Resources Study Newsletter #3 (September 2009)

Manhattan Project Sites Special Resources Study Summary of Conclusions (undated)

Manhattan Project Sites Draft Special Resource Study/Environmental Assessment (November 2009)

Manhattan Project Sites FONSI Special Resource Study/Environmental Assessment (September 2010)

Memorandum of Agreement Between the United States Department of the Interior and the United States Department of Energy for the Manhattan Project National Historical Park (Draft, July 2015)

Multiple Missions: The 300 Area in Hanford Site History (M.S. Gerber, September 1993)

National Register of Historic Places Nomination Forms

Bear Creek Road Checking Station (Kimberley A. Murphy, April 5, 1991)

Bethel Valley Road Checking Station (Kimberley A. Murphy, April 5, 1991)

Freels Cabin (Kimberley A. Murphy and Philip Thomason, April 5, 1991)

George Jones Memorial Baptist Church (Kimberley A. Murphy and Philip Thomason, April 5, 1991)

Hanford B Reactor (J.C. Chatters, November 13, 1989)

Historic and Architectural Resources of Oak Ridge, Tennessee (Kimberley A. Murphy and Philip Thomason, April 5, 1991)

Homestead and Ranch School Era Roads and Trails of Los Alamos, New Mexico (Dorothy Hoard, February 2003)

J.B. Jones House (Philip Thomason and Kimberley A. Murphy, April 5, 1991)

Los Alamos Scientific Laboratory (Richard Greenwood, January 14, 1974)

Luther Brannon House (Owen Hackworth House) (Kimberley A. Murphy, April 5, 1991)

New Bethel Baptist Church (Kimberley A. Murphy and Philip Thomason, April 5, 1991)

Oak Ridge Turnpike Checking Station (Kimberley A. Murphy, April 5, 1991)

Woodland-Scarboro Historic District (Kimberley A. Murphy, April 5, 1991)

X-10 Reactor, Graphite Reactor (Polly M. Rettig, November 1965)


Los Alamos:
2016: AugustOctober

Oak Ridge:
2015: December
2016: JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
2017: JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovember
2018: JanuaryFebruaryAprilMayJuneJulyAugustSeptemberOctoberNovember
2019: FebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember
2020: JanuaryFebruaryMarchAprilMayJuneJulyAugustSeptemberOctoberNovemberDecember

Nuclear Technologies and Nuclear Communities: A History of Hanford and the Tri-Cities, 1943-1993 (John M. Findlay and Bruce Hevly, February 1995)

Park Newspaper: Oak Ridge: 20162017201820192020

Scholars' Forum Report, November 9-10, 2015, Manhattan Project National Historical Park (c2015)

The History and Ethics Behind The Manhattan Project (Miguel A. Bracchini, April 30, 1997)

The Manhattan Project: Making the Atomic Bomb (F.G. Gosling, Department of Energy, January 2010)

The Plutonium Production Story at the Hanford Site: Processes and Facilities Hitory (M.S. Gerber, June 1996)

Work at Hanford 1943-1983 (W.J. Dowis, June 1, 1986)

Handbooks ◆ Books expand section


Last Updated: 14-Aug-2021