During August of 1942, the United States began developing atomic bombs to use during World War II. The project was named the Manhattan Project because it was based in New York City and the surrounding cities. Later, the project spread to Oak Ridge, Tennessee. The U.S. worked among the United Kingdom and Canada to create more effective weapons. The second World War included two groups of countries: one group (Allies) included Australia, Britain, Canada, China, India, New Zealand, the Soviet Union, and the United States; the other group (Axis Powers) included Italy, Germany, and Japan. The United States, United Kingdom, and Canada developed two different types of atomic bombs: uranium bombs and plutonium bombs. Natural uranium contains 99.3%