We had one in our neighborhood, about 8 blocks from home. When we were kids, if we were lucky enough to get out after dark and able to stay out a while, we would walk down there. We had to cross a highway to get there, and if our parents knew we'd get in trouble. But there was a golf course directly behind the theater, and we'd pull a bench from the course up to the back fence, and watch the show.
I had a paper route when I was a teenager, and I'd deliver papers from my Schwinn Orange Crate, and later, from my 10 speed Schwinn Continental. If I got done early, I'd pedal down to the drive-in.
There was a couple of big, mean, brothers my age that cleaned up the drive-in parking lot the morning after shows. You had to get there early to beat them to the lot. But if you did... There were always cans of un-opened beer, partially full bottles of Boones Farm, and all kinds of assorted goodies. It was a teenagers paradise. I'd make a quick swing through, throw the best stuff in my paper sack, and pedal home before the clean-up crew got there. I'd ditch the stash somewhere on the banks of the creek that wound through our neighboorhood park. We'd come back later and pretend we actually liked the stuff.
Later, when we were actually driving, we hit that drive-in with buddies and dates. I saw "Star Wars" for the first time there. Yet another memorable night was spent with a few friends, beer, and other leafy "illicit substances". We watched "Marathon Man". The sound of that dentist's drill was absolutely horrific.
All in all, it was a spot of significant memories for this Product Of The Seventies.