[SampleMan]

I had no idea Albuquerque was at 52,800,000 ft., or are you just tall? You did say miles.

Many low earth orbit sats are in fact at only a few hundred miles up.

My original point is that the exit velocity for a rail gun will be so high that atmospheric loading requirements will increase strength requirements. Starting the ascent at or above 10,000 ft, reduces that by half. There is also the engineering problem of burying that much structure. Much easier to build it above ground. Of course the vehicle would need to be in a contained tube, which is itself kept at less than normal atmospheric pressure. The less the better.

[The Red Zone]

Tunnels have been dynamited and bored for roadways much further than 2 miles.