The Manhattan Project was the military program that developed the atomic bomb. This project was considered by most people to be a “conspiracy theory” for years, until the bombs eventually dropped. Whole towns were built to test the first nuclear weapons.
All of the residents were sworn to secrecy and spread out between one of the 30 testing sites across North America and the UK. The Manhattan project started out as a small testing operation in 1939 but in the few years it was in operation it grew to have over 130,000 people, all under strict secrecy.
One of these sites was in Washington state, and the leftover radioactive waste is still posing a threat today.
source - http://intellihub.com/2013/04/03/remnants-of-the-manhattan-project-is-leaking-radioactive-waste-in-washington-state/