Trump supports mass incarceration. This chart shows why that may not matter.

President Donald Trump’s election signaled the end of criminal justice reform. He has long been “tough on crime,” believing that punitive policing tactics and longer prison sentences are the antidote to crime in America — even as they’ve made the country the world’s leader in incarceration.

But there’s some good news for criminal justice reformers: While Trump is indeed “tough on crime,” a new chart from the Prison Policy Initiative suggests that may not matter much.

The pie chart (released on March 14, which is Pi Day; get it?) shows just how much of mass incarceration is local and state-based. Around 86 percent of people in prison and jail are in either a local or state facility, while the remaining 14 percent are in a federal one.

As president, Trump will only have direct control over the federal prison system. Based on the chart, that means that no matter what he does, he’ll only affect a small percentage of the prison population.

The federal government does have some say in the local and state justice systems, since it can incentivize them through grants to change their policies. But studies suggest these kinds of financial incentives don’t really work.

For example, the 1994 federal crime law encouraged states to adopt harsher “truth-in-sentencing” provisions that mandate inmates serve a certain amount of their sentence before they’re eligible for early release. But multiple reports by the Government Accountability Office found that, in reality, these incentives had little effect on states’ policies; instead, states had either already moved ahead with truth-in-sentencing laws before the 1994 law passed, or they decided that the federal incentives weren’t enough to pursue a policy they disagreed with. Put another way, states led the charge and dictated their own policies, regardless of what the federal government did.

There’s a similar story with criminal justice reform today. While the federal government has failed to pass significant criminal justice reform due to congressional gridlock, states have moved forward with all sorts of reforms — with states from deep blue California to deep red Georgia pushing to cut prison populations over the past few years.

Even this doesn’t tell the full story, because a lot of the criminal justice system occurs at local levels. While states can pass laws, it’s ultimately up to local prosecutors and police to actually enforce those laws, and these local officials have a lot of discretion. One striking example: In 2014, former Brooklyn District Attorney Kenneth Thompson announced that he would no longer enforce low-level marijuana arrests. Marijuana was still illegal in New York at the time, but the local prosecutor wasn’t having it.

As John Pfaff of Fordham University wrote in his book Locked In, “In other words, a national story is too blunt of an instrument to convey the complexity of the criminal justice system in the United States. A state story is an improvement, but it still misses a lot of detail. Ideally, we would need to tell 3,144 stories, one for each county in the United States.”

So it will be up to the cities, counties, and states to really lead the charge on prison reform. That will still require some hard choices: The pie chart, for one, shows that only about 20 percent of inmates are in for drug offenses and around 19 percent are in for property offenses, while about 40 percent are in for violent crimes — yet most reform efforts so far have focused on property and particularly drug offenses, and neglected the bulk of prisoners serving a lot of time for violent crimes.

But those hard choices won’t require Trump’s approval.