The Manhattan Project

During World War II, the Manhattan Project was a research and development project that resulted in the first nuclear weapons. It was led by the United States, with the United Kingdom and Canada on board. Robert Oppenheimer, a nuclear scientist, was the director of the Los Alamos Laboratory, which created the bombs. The Manhattan District was given to the Army component of the project since its early headquarters were in Manhattan; the placename subsequently replaced the official codename for the whole project, Development of Substitute Materials.

The project absorbed its previous British equivalent, Tube Alloys, along the way. The Manhattan Project began modestly in 1939 but eventually developed to employ over 130,000 people and cost about $2 billion (around $23 billion in 2020). Building factories and creating fissile material accounted for almost 90% of the cost, with weapons development and manufacture accounting for less than 10%. More than thirty locations in the United States, the United Kingdom, and Canada were used for research and production.

Cost: $2 billion