Is violent crime on the rise, or isn't it? A look at Trump and Sessions' math

After being sworn in last week, newly confirmed United States Attorney General Jeff Sessions told Americans he was concerned about rising violent crime rates – what he called a "dangerous trend."

The comments sounded a lot like those from Sessions' boss, President Donald Trump, who promised to end "American carnage" during his inauguration speech last month, and repeatedly warned about a surge in violence throughout his campaign.

News outlets have been quick to correct the record. Crime statistics don't back the claims that violent crime is on the rise. Rather, law enforcement data show these crimes have been on a steep decline since the 1990s and have hit their lowest points in decades.

But both of these cannot be true. Either violent crime is rising or falling.

And the answer matters. Both Sessions and Trump wield great power in driving the national conversation and influencing criminal justice policy.

These policies come at great cost to the taxpayers – the War on Drugs is estimated to have cost more than $1 trillion – and the only way to effectively combat threats to the nation come from fact-based policies, said Ames Grawert, who studies crime trends as counsel for the Brennan Center for Justice in New York.

"If you start with bad facts, you're going to get bad policies that might make the country less safe, that might strain relationships further between police and communities of color, that send more people to prison for little reason," Grawert said.

First, let's look at Minnesota. The chart below reflects murders, robberies, rapes and aggravated assaults dating back to 1980. The data come from the FBI's "Uniform Crime Reports," the most comprehensive data on crime nationwide. To account for a rising population, these are calculated as each incident per 100,000 residents.

The data show violent crime rising in the 1980s and peaking around the mid-90s – an era commonly known as the "Murderapolis" years in the Twin Cities. Violent crime spiked again in the mid-2000s, and has since been in decline through 2015.

There appears to be a slight increase in rape and murder from 2014 to 2015, but these rates were still very low compared to the '90s. And a one-year bump isn't enough to prove a trend.

Now, let's examine these trends nationally. According to UCR statistics, violent crime in the United States peaked in the early 1990s. The data reflect a significant drop in all violent crime – with a few years of fluctuation, particularly in the mid-2000s – all the way until 2015. There is some mystery on what exactly accounts for the decline, though most credit it to statistics-based crime fighting tools like "Compstat," growth of income and a trend toward decreased drinking.

There were some increases from 2014 to 2015 -- and these aren't insignificant.

Of course, there are exceptions. Trump has called Chicago out by name – even threatened to send in the feds – due to the city's reputation for violent crime. The federal data show the murder and assault rates in Chicago have indeed gone up over the past couple years, and a new analysis from the Economist suggests it continued to rise in 2016.

Yet even with this increase, murder and assault rates are still lower than in the '90s. Other violent crimes, like robberies, were down in Chicago. And criminal justice experts point out that an increase in one city doesn't amount to a nationwide trend.

"Not every city is Chicago," said Grawert of the Brennan Center. "The experience of these few cities is just not the experience of the country as a whole."

Here, charting those cities on the same chart with the state and the nation shows that - different places can have wildly different murder rates, even from year to year.

So this brings us back to our original question: what are Sessions and Trump talking about when they say violent crime is rising?

"They only make sense as an overreaction to a clear-and-present danger," he said. "So I think he needs to make the country feel less safe than it is to sell some of these policies."