I agree. Plus, gasoline does have a shelf life and the apocalypse is almost 2 years running now, not to mention the gas guzzlers the Saviors are driving. But it is a show about zombies, so if you can believe that, i guess we have to accept that gasoline is still available.
FYI...this is what I found online regarding the "Alexandria safe-zone"
The Alexandria Safe-Zone, or simply Alexandria, is a few blocks of cleared streets in Alexandria, Virginia, about six miles south from Washington D.C..