Humans: a Drought-Tolerant Species?

One thing about dryness - it preserves the records of human activity and subsequent abandonment of regions. Many a monument lay in ruins as testaments of once-thriving civilizations and cultures that eventually caused - or just happened to be in the path of - longterm drought. Innovation allowed the early Egyptians to take advantage of precipitation cycles far away in the highlands to flood and irrigate their desert-edge crops. But mankind seems to be blind to limits and overuse of resources, leaving ourselves vulnerable to the consequences of our own excesses and Nature's whim.
Phoenix and Las Vegas come to mind when I think of huge human settlement of locations that don't seem to be meant to support such a thing. Vegas, of course, is the most ridiculous example in the world of outright squandering of scarce resources. Gamblers will, of course, support that waste for a while, and the sheer number of residents invested in living in the Valley of the Sun will keep Phoenix going for years. But some less conspicuous locations in the U.S. have been suffering drought for long enough to have their condition labeled extreme by the US Department of Agriculture.

Check out this map. I'll be keeping track of how these conditions impact the farmers, ranchers and residents in these areas as their droughts extend. As history has shown us, people can only tolerate such conditions for so long, even if you believe they're simply part of natural climatic cycles.