These many DoD outposts aren’t why the Economic Development Corporation of Utah says the state’s a great place for data centers. Instead, they mention that it's generally untouched by natural disasters, and it’s a pretty secure region given that it’s very isolated and spacious. It’s also in proximity to a lot of Internet backbone, and the state “has a long and distinguished history in the high-tech industry,” which presumably makes it easier to find skilled IT workers.
That long and distinguished history really kicked off around 1969, when the University of Utah was made one of the four original nodes of ARPANET. Its presence in that initial constellation (the only non-California node in the network) was largely due to the efforts of David C. Evans, a Utah native who had been teaching at the University of California, Berkeley, when ARPA was just getting started. The U of U lured him back to Salt Lake to create and chair their new computer-science program. He brought his DoD connections with him, and an ARPA contract named “Graphical Man/Machine Communications” that funded a lot of the department's early activities.
Evans's reports to the DoD and papers published under the contract are available online via the university library. They’re pretty amazing documents of Internet and computer-graphics history—one features an abstract of Alan Kay’s dissertation. Other U of U computer-science alumnae have been involved in the formation of companies like Silicon Graphics, Pixar, and Adobe.
Today, the University of Utah's computer-science program continues to have interesting DoD ties. When the NSA Data Center was initially being built, the agency worked with the university to develop a data-center-engineering certificate program, essentially building a pipeline for students to continue to support Utah's data-center industry, with one data center in particular presumably needing a lot of support (U of U also has a Big Data certificate program; weirdly, neither of these programs currently require any ethics coursework).