Gray Butte may be the largest private unmanned aerial vehicle (UAV) airport in the USA. It is General Atomics' main test center, where the company’s Predator and Reaper UAVs are regularly flown. By the early 1980s, a World War II-era remote training field here was developed into a radar cross section test site by McDonnell Douglas, to develop and test stealth technologies. (Northrop and Lockheed have similar facilities in the Antelope Valley as well.) After some years of disuse, the facility was purchased by General Atomics in the 2000s, significantly expanded, and turned into a UAV assembly and test facility.