Originally Posted by gengar

At LAS, all gates are connected airside but immigration/customs will kick you out at T3 and DL does ground handling out of T1. So long as you don't need BPs/ticketing assistance and do not have checked baggage (or assuming VS still interlines to DL or you are on one ticket so can simply drop off your checked-through bags after exiting customs), you can re-enter airside in T3 and proceed to the DL gates in Terminal D. 1hr50m should be plenty of time.

Be aware that getting from T3 to T1 while landside is not that convenient; a free shuttle service is provided but only runs every 15 minutes or so.