There’s a good chance that you’re familiar with the Homeland Security Advisory System (HSAS), even if you don’t know it by name. Replaced in 2011 by the National Terrorism Advisory System, it was that color-coded notification system developed in the wake of 9/11 that ostensibly functioned to alert the public of a probable terrorist threat to the United States. Green indicated a low risk of attack; blue, a general risk; yellow, an elevated risk; orange, a high risk; and red, a severe risk. In spite of the supposed “generality” of the blue level, the advisory had not once been lower than an “elevated” yellow in its nine years of existence. Instead, it vacillated between yellow and orange for the most part, though it did strike red in 2006.