Final answer:
The Manhattan Project was a large top-secret research project during World War II to develop the first atomic bomb. It employed many people across multiple sites in the United States.
Step-by-step explanation:
The Manhattan Project was a large project that employed many people at several sites across the United States. It was a top-secret research and development project during World War II to develop the first atomic bomb. The project was led by the United States, with assistance from the United Kingdom and Canada.
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