Laramie, Wyoming

The claim: FEMA detention facility

What it really is: Using Google maps I've seen several several building there (mainly schools and warehouses) that to a conspiracy theorist might actually misidentify as a FEMA camp.

The population of the city is also growing, and now has over 31,000 people. Considering the amount of people living there, it's doubtful such a facility could actually remain hidden without getting much more attention.