Originally Posted by the_traveler
Don't some airlines in the US also use both the front and back doors for boarding and unloading?

IIRC, UA and WN did/does/will at some airports.
This happens quite often at SJC. The planes which end up on a stand without a jetway have stairs brought up. They very often unload 737/A319/A320 aircraft from the forward and rear door. I have deplaned quite a few AS aircraft from the rear and some US A320s this way as well at SJC.