 So the US-Mexico border is one of the central case studies in the book. I've been really lucky to have visited a few years ago and actually just recently at the end of May to kind of see how technologies are changing the way that people cross borders. And at the US-Mexico border in particular, it's a fascinating place to do this work because you can actually see some of this technology firsthand. I mean, first of all, you can drive to the border wall and see the surveillance towers. Sometimes you can even hear drones.