Crime scene tape secures a shooting scene where 5 people were reported to have been shot on September 28, 2015 in Chicago, Illinois.  (Scott Olson/Getty Images)

Distilling one bit of data down to its briefest articulation, a new report from the Brennan Center for Justice seems to offer Donald Trump some evidence for his repeated insistence that crime is "out of control." It's a critical argument for the Republican nominee. His presidential campaign is based in part on the idea that the United States both faces a deteriorating public safety picture and that only he is poised to address the problem. (Last week, Trump received the endorsement of the Fraternal Order of Police.)

That distilled bit of data? The Brennan Center anticipates that the national murder rate will rise 13.1 percent in 2016 over 2015.

And the catch? Crime overall will remain flat. And half of the increase this year, the Center's analysis suggests, will be due to the spike in Chicago alone. Half of the 31.5 percent increase in murders between 2014 and 2016 is solely a function of increases in Chicago, Baltimore and Washington -- cities that Trump often references during campaign appearances.

The report updates preliminary analysis from the Center earlier this year with new data. At that point, the Center's analysis suggested that "while Americans in urban areas have experienced more murders this year than last year, they are safer than they were five years ago and much safer than they were 25 years ago." The new numbers don't change that core finding. "These findings undercut media reports referring to crime as 'out of control,'" the new report reads, "or heralding a new nationwide crime wave. But the data do call attention to specific cities, especially Chicago, and an urgent need to address violence there."

Particularly relative to the long-term trend the Brennan Center demonstrated only a subtle change in the national crime rate, anticipating a 1.3 percent increase this year.

Crime per 100,000 people in the 30 largest cities

(Brennan Center for Justice)

Again, the murder rate increased much more significantly, though the overall rate is still expected to be near recent lows.

Murders per 100,000 people in the 30 largest cities

(Brennan Center for Justice)

Interestingly, murders in Baltimore and Washington, which contributed to the two-year jump in the murder rate, are both projected to drop this year (by about 10 and 11 percent, respectively), replaced by sharp increases in cities like San Jose, Calif. That's a bit deceptive, too. The murder rate in America's tenth-largest city is expected to increase by 70.6 percent -- thanks to a relatively modest 21 more murders in a city of one million people.

There's no real link between increases or decreases in the crime rate and increases or decreases in the number of murders in a city.

Change in crime vs. murder rates, 2015 to 2016

(Brennan Center for Justice)

Understandably, the Center tried to identify why Chicago was such an outlier in its murder rate. It identified a few possibilities, but noted that data wasn't available to offer concrete answers. One issue is that a relatively small group of some 1,400 people in the city were responsible for much of the violence. Another possible factor was a decrease in the number of police. More broadly, the Center pointed to socioeconomic conditions, decreases in police staffing levels and a frayed relationship between the police and communities as possible -- but unproven -- factors in crime increases in some cities.

It's hard to overstate the irony in the city of Chicago, home of President Obama and helmed by one of Obama's close political allies, being one of the strongest reasons that Trump can point to an increase in murder to make a rhetorical point on the campaign trail. Regardless of the numbers beneath the numbers -- crime overall staying flat and Chicago being an outlier -- Trump can still point to a number that suggests that his point is valid.

The Brennan Center's report argues in advance that this argument is unfounded. "[T]here is not a nationwide crime wave, or rising violence across American cities," it concludes. "Warnings of a coming crime wave may be provocative, but they are not supported by the evidence."

But they are indeed provocative. So expect them to continue.