Originally Posted by skydisaster

To understand the Allegiant route map, you have to understand the Allegiant business model. The model is to take passengers from small town USA to vacation destinations. The orange dots are the vacation destinations. Airplanes (and crews) are based at the vacation destinations and fly out to the small towns and back. The limitation to that has been that there is only so much ramp space at the vacation destination, so in the larger small towns that feed multiple vacation destinations, Allegiant has opened small bases (usually 1-2 airplanes). These are locations like AVL, CVG, etc.
Many of the vacation destinations (like AUS and San Juan) are not big enough to be a base yet so they are served by other bases.

VPS and MYR are seasonal vacation destinations and are staffed with crews and airplanes that have been TDY'd from other bases. I suspect VPS will become permanent soon, but it is not yet a permanent base.