The Manhattan Project was a top-secret government research project during World War II aimed at developing the world’s first nuclear weapon. The project was led by the United States, with the assistance of the United Kingdom and Canada, and resulted in the creation of the atomic bombs that were used to end the war. The Tri-Cities, Washington, and Hanford were significant players in the Manhattan Project, as they were home to the Hanford Engineering Works, a secret facility responsible for producing the plutonium used in the atomic bomb. The impact of the Manhattan Project on the Tri-Cities, Washington, and Hanford was immense, as the project brought a large influx of jobs and economic growth to the area, and forever changed the course of history. The Hanford site continues to be a major center for nuclear research and development to this day, and its role in the Manhattan Project is an important part of the region’s history and cultural heritage.