America is safer than it was 20 years ago. Really. Still, White Americans (and many Black Americans, for that matter) believe there's more violent crime than there actually is, and that Blacks are largely responsible for it. In fact, nearly half of White Americans polled believe that violent crime has increased in the last 20 years. Another 13 percent believe that it's stayed the same. Less than a quarter of Whites realize there are less violent crimes today than there were in the 90s when the crack epidemic and gang violence were at their height.

Even more, Whites overestimate just how much Blacks are involved in "serious street crime" and, on average, believe that Black people commit a larger proportion of crime than whites do. According to a 2012 study by researchers at the University at Albany, Whites significantly overestimate the share of armed robberies, break-ins and drug crimes committed by Black people.

So, this is how we get to Rudy Giuliani, a man once in charge of the nation's largest police force, insisting that, "White police officers wouldn't be [in Black neighborhoods] if [Blacks] weren't killing each other" as a justification for the killings of unarmed Black people. This is how we get Stop and Frisk policies, Tamir Rice shot dead in a park, John Crawford shot dead in Wal-Mart, Akai Gurley shot dead in a dark stairwell, Miriam Carey shot dead outside the White House (the list goes on and on.) And this is also how we get a grand jury reviewing video of Eric Garner choked to death and seeing no evidence of a crime. Each is an example of racist policing based on the assumption of threat.

In a country that has identified Black people as its criminal element, public safety (and perceived security) is more tied to the suppression of Blacks than it is to the suppression of crime. And as long as the public insists on its myth of Black criminality—almost as an article of faith—police practices will be impossible to reform.