As we end the 15th year of what award-winning reporter Steven Brill, in feature to be published next month in The Atlantic, calls the September 12 Era, we can look back at a series of heroic efforts to plug stunning security gaps—as well as a series of billion-dollar boondoggles borne out of an unprecedented mix of understandable fear, Beltway greed, bureaucracy, and political posturing. What have we done well? Where have we gone wrong? How have we adjusted to the perceived shift in the threat from extravagant plots, like 9/11, to one-off home-grown attacks?