In fact Associate, they’ve probably got “Secret Tech” bases all over America which handle sensetive technology. Due to the fact that Area 51 does exist and is quite easily found (See new Google World or whatever it’s called which has better satellite images than Google maps, look around Groome Lake) it would make sense for you guys to keep the real sneaky-beaky stuff somewhere else.
Of course, besides all this we have the fact that UFO’s only started to be descibred as “Flying Saucers” aroung 1945-ish, which is a coincidence considering that the Germans had been testing a saucer shaped craft which was later adopted and tested by both the US and British governments. What better way to hide the development of new aero-technology than by claiming that the sightings were all craft from outer space?