>And there's not much selection bias in the old footage you see of crowds walking city streets at the turn-of-the-century. Are you sure? What part of town were

>And there's not much selection bias in the old footage you see of crowds walking city streets at the turn-of-the-century. Are you sure? What part of town were the photos usually taken, and for what purpose? I would actually be very surprised if there weren't selection bias in where, when and why such photos were taken.