Phoenix, city on the edge of a desert
If you live in the Phoenix area, like I do, and have ever wondered why a city was built "way out in the middle of the desert", you need to take a second look at the geography. Phoenix is on the edge of a desert. The map above shows a satellite view of the Sonoran Desert. To the lower left is the Gulf of California, and at right are the uplifted areas of Arizona. The arrow shows the Salt River Valley, which is where Phoenix is. So, from a geographical point of view, Phoenix is in a wonderful position to take advantage of the annual runoff from the uplifted areas. The water flows from northeast to southwest, and empties out into the ocean at the Gulf of California. It may not feel like it when you're driving around Phoenix, but Arizona tilts towards down (towards sea level) southwest. The main advantage that the pioneers saw in the Salt River Valley was the fertility of the soil, watered annually by flooding. The trick was, and is, how to control that flooding, ca