After two years of unsettling increases, America’s crime and murder rates may have declined in 2017.

A new report by the Brennan Center for Justice looked at crime and murder rates in the 30 largest US cities, updating figures from another report released in September with more data for the rest of the year. Over the past two years, Brennan had found increases — sometimes sharp rises — in the violent crime and murder rates. Many feared this was a reversal from the past several decades of crime decreases, which put the 2014 US murder rate in particular at the lowest it’s been since at least the 1960s.

So it’s good news that the opposite seems to be true this year. According to Brennan’s estimates, the overall crime rate fell by 2.7 percent, the violent crime rate dropped by 1.1 percent, and the murder rate declined by 5.6 percent in 2017.

“Large decreases this year in Chicago and Detroit, as well as small decreases in other cities, contributed to this decline,” Brennan found. “The murder rate in Chicago — which increased significantly in 2015 and 2016 — is projected to decline by 11.9 percent in 2017. It remains 62.4 percent above 2014 levels. The murder rate in Detroit is estimated to fall by 9.8 percent. New York City’s murder rate will also decline again, to 3.3 killings per 100,000 people.”

As the report notes, some cities’ murder rates, even after overall decreases this year, will still be above numbers from a couple years ago — which, according to Brennan, shows “a need for evidence-based solutions to violent crime in these areas.” (For more on what works to combat crime and violence, read Vox’s explainer.)

One caveat: These are preliminary figures, based on data from 29 of the 30 largest cities (Phoenix didn’t provide 2017 statistics to Brennan). The full official numbers for the entire US, compiled by the FBI, will come out later next year. Generally, however, Brennan’s reports have done a good job predicting overall national trends in the past few years.

And the news, overall, is good.

The past two years of increases may have been blips

The past two years’ increases in the murder rate got a lot of attention, with President Donald Trump and Attorney General Jeff Sessions often bringing them up in speeches to justify “tough on crime” policies. But before they’ve been able to implement such policies and let them take root, especially in local and state jurisdictions where federal policymakers have very limited power, these rates appear to be coming down.

Criminologists still aren’t sure why murder in particular appeared to spike so much in 2015 and 2016. Some argued that there might have been a “Ferguson effect,” named after the city that exploded into protests over the police shooting of Michael Brown: Due to protests against police brutality over the past few years, police were, the theory goes, scared off from doing proactive policing, emboldening criminals.

Other experts argued a different kind of Ferguson effect: The demonstrations over police led to elevated distrust in law enforcement, which makes it much harder for police to solve and prevent crimes.

Yet many criminologists cautioned that it’s also possible that the two years’ increases were blips in the data. This isn’t unprecedented; in 2005 and 2006, the murder rate in the US increased before continuing its long-term decline — to new record lows — in the ensuing years.

Since the murder rate in particular is generally low, it’s prone to large statistical fluctuations. As one example, New Orleans–based crime analyst Jeff Asher previously told me that he expected the 2016 mass shooting at a gay nightclub in Orlando, Florida, in which 50 died, to lead to a massive increase in the murder rate in the city, even though it was just one particularly horrific event.

That’s why criminologists generally demand several years of data before they declare a significant crime trend.

It now looks possible — though we’ll need more years of data to confirm — that 2015 and 2016 were replays of 2005 and 2006. If that holds, then perhaps the US isn’t in the middle of the “American carnage” that Trump warned about.