History

The Project

Concerned that Nazi scientists were creating a bomb capable of horrific destruction, the U.S. government launched the Manhattan Project to develop an atomic bomb before the Germans could. They tasked the best scientists and engineers available to harness the power of the atom, creating the atomic bomb.

The Manhattan Project consisted of three main sites: Oak Ridge, Tennessee; Hanford, Washington; and Los Alamos, New Mexico. Oak Ridge was responsible for the enrichment of uranium, U-235, which ultimately fueled the atomic bomb “Little Boy.” The site at Hanford created plutonium, which was used to create the atomic bomb “Fat Man.” Scientists and engineers developed weapon technology to use these enriched nuclear materials at Los Alamos.

On August 6, 1945, the U.S. dropped Little Boy on the Japanese city of Hiroshima and three days later dropped Fat Man on Nagasaki, Japan.

Between the three locations, the Manhattan Project cost more than $2 billion, equivalent to roughly $26 billion in 2015 dollars, and employed more than 130,000 men and women.

The Purpose

While the government launched the Manhattan Project to develop atomic weapons that would put an end to World War II, the project also became a catalyst for extraordinary advances in a variety of fields including medicine, power generation, and space exploration.

The park is not intended to celebrate the atomic bomb; rather, its purpose is to preserve the legacies and histories of people, events, science, and engineering that changed the world forever.

August, 1939

A letter to the President
Read more

December, 1941

The Japanese attack Pearl Harbor
Read more

September, 1942

"Site X" is approved in East Tennessee
Read more

November, 1942

"Site Y" is designated in Los Alamos, New Mexico
Read more

January, 1943

"Site W" is chosen in southern Washington
Read more

February, 1943

X-10 reactor and Y-12 plant
Read more

April, 1943

Bomb design begins at Los Alamos site.
Read more

July, 1943

Manhattan Project sites proclaimed military districts
Read more

November, 1943

X-10 reactor in Oak Ridge reaches criticality
Read more

February, 1944

First enriched U-235 is delivered to Los Alamos
Read more

September, 1944

Hanford's Reactor B goes critical
Read more

February, 1945

Hanford delivers plutonium-239 to Los Alamos
Read more

May, 1945

European theater of WW2 ends
Read more

July, 1945

Test device detonated near Alamogordo, NM
Read more

August, 1945

Atomic bombs are dropped on Japan
Read more

September, 1945

Japan surrenders to the Allies
Read more

January, 1948

Atomic Energy Act goes into effect
Read more

November, 2015

Establishment of Manhattan Project National Historical Park
Read more
X