Ghost towns.

Every couple hundred years, the earth gets a little full. People just keep multiplying and multiplying, and soon there's not really enough space to fit them all. Usually when this happens, the human race becomes such a big target that there's something that happens to thin us out immensely. There was PTA here recently. There was a plague a few hundred years ago. There have been many different happenings that have brought us to our knees, all the way back to a traumatizing flood around ten thousand years ago. It's amazing to be part of the few who have seen both sides of one of these happenings. I was old enough to remember what the world looked like full. No empty towns, cities, counties... So it's still weird when I walk into a place that looks habitable, but there are no people to inhabit them.
Ghost towns are creepy.
That's why, when we got to F4, needless to say I was creeped out. The place looks like a military town. Gates and fences all around, checkpoints to get in at any entry, you've seen the places. But there was no one anywhere. There weren't even any dead cars like there are in most abandoned towns. It was like there was some mass evacuation. John and I drove into the compound and found the phone. There's one on every safe base, and they work the way they did in the old days, with an operator and everything. We patched through to home, and told them what was going on.

We talked to Natalie Max, who is basically the head of our base.
"We made it, but there's a bit of a problem..." I started.
"What's the issue? You have permission to offer them whatever they need to get the food and fuel to last us til the next truck. You'll be back tomorrow night, right? Don't forget we need medicine, our coolers shut down so all the penicillin and insulin is unusable."
"Well, that's just it, Natalie, there's no one to trade with." John said.
"What do you mean, no one? Is their commander off base?"
"No, Natalie," I said, "there's no one, literally not a single person here. In the whole place, nobody living or otherwise anywhere. It's a ghost town."
"Well, is there any food or energy there?"
"We haven't checked yet," I answered.
"What about the people?" John interrupted, "Don't you even care that hundreds of people are just gone?"
"Of course I care, John," Natalie answered, "But right now we don't have the time to worry about that. I've got to secure our people before I can worry about them. We can't even order the medicines that our people need til the next truck gets here, then it's at least another week til it actually arrives. Dahlia, Belle is one of the people who needs medication, you know how important this is."
"John! She's right," I stopped him before the argument could get any more heated, "You've both got valid points, and we'll investigate as soon as possible, but we have to save the people we know we can save first, and worry about the others as soon as possible. If we worry about everything at once, we'll get nothing done."
"Fine. Let's get on it, then."
"All right, so you have the list, right?" Natalie asked.
"Yes, ma'am. We'll call back when we head out." I answered.
"All right, good luck to you, and hurry."