[TigeriusKirk]

The trainer versions go in and out of Mather fairly often. I assume they're based at Beale AFB and just use Mather for short training hops.

[cornellwright]

The U2 I saw at Mather was based a Beale (as were the Air Force folks exhibiting it). They said the U2s get rotated in and out of service/training and that this unit had been all over the world.

[CalChris]

Mather AFB has been closed since 1993.

[TigeriusKirk]

At which point it became Sacramento Mather Airport, where the trainers fly in and out of from time to time.