Most plausible comment I found on the internet was the government lost something in that trapezoid and doesn't want anyone to fly over it and find it until it's collected.

Ah, so an alien's contact lens

Roswel is a few hours away by car. Interesting theory but they would lose it there.

Broken Arrow?

Quick, someone call Skinner and get Mulder and Scully on the case!

[deleted]