On 7 February 2017, President Trump held a roundtable discussion with county sheriffs from around the United States in which he cited a chilling crime statistic as a reason for inviting the sheriffs to the White House:
... the murder rate in our country is the highest it’s been in 47 years, right? Did you know that? Forty-seven years. I used to use that -- I’d say that in a speech and everybody was surprised, because the press doesn’t tell it like it is. It wasn’t to their advantage to say that. But the murder rate is the highest it’s been in, I guess, from 45 to 47 years.
Trump made similar claims during the 2016 presidential campaign. On 26 October 2016, for example, he stated the following to a crowd in Charlotte, North Carolina:
The problem is not the presence of police, but the absence of police. We need really a great group of people to keep you safe, to keep us all safe, to keep us all safe. You know the murder rate in the United States, I don’t know if you know this because the press never talks about it, is the highest it’s been, think of this, in 45 years. Nobody knows that. The murder rate, highest it’s been in 45 years.
Both versions were incorrect, however. According to the most recent FBI data available, an estimated 15,696 murders occurred in the United States in 2015, or 4.9 murders per 100,000 people. And while this was the highest murder rate in six years (compared to a range of 4.4 to 4.8 murders per 100,000 each year since 2009, when the figure was 5 per 100,000), it's less than half the historical high of 10.2 in 1980.
FBI statistics show, in fact, that the 2015 murder rate was among the lowest of the past 47 years, and indeed the lowest of any year between 1965 and 2009.
It's likely that President Trump erred by conflating the murder rate itself with the size of the year-over-year increase in the murder rate. That is, the 2015 rate (4.9 per 100,000) marked an increase of approximately 11 percent over the previous year's murder rate (4.4 per 100,000), which, it would be accurate to say, is the highest year-over-year rate of increase in 45 years. On at least one other occasion, during his so-called "victory tour" after the 2016 election, Trump stated the statistic correctly: "On crime, the murder rate has experienced its largest increase in 45 years."
Trump aide Kellyanne Conway appeared to confirm that he had conflated the statistics during a subsequent interview on CNN: “When he talks about the 47 years and the rate, I’m handed the information, I think you referred to it as well, that we have had an increase from 2014 to 2015," she told host Jake Tapper.