According to the infographic from Wikibon below (and originally posted on the Built In Chicago blog), Chicago has two of the largest data centers in the United States. 

According to CenturyLink, nearly 3 billion people will be online in 2015, pushing the data created and shared to nearly eight zettabytes. How much data is that? CenturyLink provides a very interesting infographic (below) to put it all in context.