Current US President Donald Trump is on record as repeatedly saying that "The murder rate is the highest it's been in I guess 45-47 years."
Is that true?
NO! The EXACT OPPOSITE is true.
According to this comprehensive listing showing data from 1960 to 2015 shows the highest absolute number of murders (24,700) occurred in 1991. The highest per capita rate (10.2) occurred in 1980. If anything, the data shows that the period of 2010 to 2015 has been historically LOW for murders.
Pew has similar numbers. As well as showing that people are totally unaware of the fact that rates are at historic lows.
As per ff524's comment: "Law enforcement agencies tabulate the number of Part I offenses brought to their attention based on records of all reports of crime received from victims, officers who discover infractions, or other sources... When, through investigation, an agency determines that complaints of crimes are unfounded or false, the agency eliminates that offense from its crime tally through an entry on the monthly report." In other words: the FBI data is reported crimes, minus reports that have been determined to be unfounded. (The "murder" category includes both murder and non-negligent manslaughter.)
So the definition isn't cherry picked either.
No, 2015 was the highest since 2009, but it was much higher previously, according to the Death Penalty Information Center.
According to the FBI Uniform Crime Reports, via Politifact, the increase in the murder rate (10.8% from 2014 to 2015) is the highest in 45 years, but obviously that is different from the quote in the OP.
Full year statistics for 2016 are not yet available, but the FBI reports that for the first half of 2016 murders were up 5.2% over the first half of 2015.
No, the US Murder Rate is not the highest it's been in the past 45 years.
According to this page from fbi.gov, the murder rate and the total number of murders for the year 2015 is lower than every year between 1996 and 2008. Note that the data for 2016 is not available yet; however Donald Trump has been quoted as saying this at least as far back as October 26th, 2016.
While I was not able to find direct numbers for the time between 1970 and 1995, Factcheck.org covered this topic after Donald Trump's October 26 speech. To quote their website directly:
According to FBI data, the rate of murder and nonnegligent manslaughter in 2015 was 4.9 per 100,000 inhabitants. That’s lower than the rate in 1970, which was 7.9 per 100,000 inhabitants, and it’s lower than the peak rate of 10.2 per 100,000 inhabitants in 1980. Overall, the rate in 2015 was lower than any other time between 1965 and 2009.
No, but the rate is increasing at its highest acceleration in 45-47 years. This might be what he meant.
The Economist has gathered murder statistics for 2016 for the 50 cities with the most murders. These places contain 15% of the country’s population and around 36% of murder victims. Our numbers show that, in 2016, murders increased in 34 of the cities we tracked. Three cities experienced a spike in deaths sharper than the 58% suffered by Chicago. Since cities tend to reflect the country as a whole, this suggests that the murder rate is rising at its fastest pace since the early 1970s