Of all the places to build a data centre, Phoenix would be somewhere close to the bottom of the list; it’s bastard hot, rarely rains and has a river with no water. In it. What’s wrong with Seattle, or Bergen?
Simply put? Proximity.
There's a view within the Industry that you need to have your content as close to the consumer as possible. Cos that extra 50-100ms is critical to keeping their custom... Putting a data centre in say Phoenix is pretty well positioned. Half way between the two major population concentrations of California and Texas.
Texas is trying to grow it's IT industry as it moves away from extracting dinosaurs from the ground, so it's also a popular location.
In Europe. Google has broken ground on a big DC in Norway. There was also an announcement, tho I can't find it now, for a DC in Norway that would consume 10% of the nations energy, and employ just 150 people...
J