San Antonio, TX
Daily, 24 Hours
Saw a sign announcing the Pig Stand as the World's first drive-in. Turned out that another Pig Stand in Dallas actually holds that honor. Also the first drive thru window, and the first to use fluorescent lighting. They also claim to have invented Texas Fried toast and to have "introduced" onion rings.
The Pig Stand I happened upon is #29, so I'm assuming there are a bunch, throughout Texas, which is good. It's just like any Texas Drive-in I've ever imagined.
There specialty is Chicken Fried steak. Good, but not quite Hoover's good.