BerTX, i'm going to have to disagree here that those are remotely the same situation. Philly has a charger to the northeast (Burlington - coming from New York), that's 41 miles away and one to the southwest (Claymont - coming from DC) which is 25 miles away. So anyone coming in to / out of Philly can get to and from that charger on one charger.
As for Seattle, they've got two chargers within 30 miles with one within 15 miles of the city center, to the north and east respectively, so unless you're coming from the south, you can again get in and back out to that charger.
San Antonio on the other hand, has 1 charger you can get to and from (San Marcos - coming from Austin/Dallas 45 miles away), while anyone trying to drive the Houston to San Antonio to Houston route or coming in from any other direction can't make the trip. Considering the fact that they'd said they'd have 2 the area by the end of the year and the amount of people who live and drive in this area, I'd consider this the largest hole in the supercharger network in the country.
It really doesn't help when you want to make inroads in to selling cars in the state, to have owners who have to tell people, "yeah, that's true, you can't drive to San Antonio and back or anywhere else you'd want to go in west Texas past there on I-10."