H. W.: Everything west of about the hundredth meridian is arid country, it's desert. And unless it is modified by human activity, it's essentially uninhabitable - at least, uninhabitable in any large scale. And so, if you want to get a lot of people in a place like ... Las Vegas, you somehow have to command enough water to get people there. Water is the critical thing.
Brian: Nevada embodies how water shaped the western states. Its largest city is Las Vegas. With two million residents, it consumes 255 million gallons of water every day. I'm only a few miles outside Las Vegas and it's plainly obvious that this is not an ideal place to build a gigantic city. It's the driest state in the United Sates and ... this is the Mojave Desert.