There are currently 12 Google data centers in the United States. When building these data centers Google had to build them less expensively then ever before. One of the main breakthroughs they had was that they determined that they didn't have to cool their server rooms as much as others had before. Running calculations they determined the temperature they could afford to run at and this along with other tricks allowed them to develop these Data Centers. Here is a video of one of their Data Centers.
Fun fact: Both Google and Facebook have huge data centers in Oregon because power is relatively cheap there (and because of tax incentives)