As a candidate and now as President, Donald Trump has promised to lock more people up. Undocumented immigrants. Drug dealers. Gang members in Chicago. But the tough on crime approach favored by President Trump won't just hurt people in cities he's painted as urban hellscapes. New research finds that the areas helping drive America's rapidly rising incarceration rates are in rural America—areas, in other words, that voted for Trump.

A new report based on data that until recently remained siloed across the country shows that even as cities like New York and Los Angeles have been reducing their jail populations, jails in rural counties---think Campbell County, Tennessee or Boone County, Arkansas---are growing exponentially.

“These places, as we saw in the election, felt overlooked and forgotten,” says study co-author Ram Subramanian, editorial director of the Vera Institute of Justice. "There are a lot of states engaged in criminal justice reform. They have to cater to these places and pay attention."

Subramanian and co-author Jacob Kang-Brown owe their discovery to Incarceration Trends, a data visualization tool built by the institute, which aggregates county-level data on the demographics of all of the country's jails. By freeing criminal justice data from the confines of so many dusty filing cabinets belonging to state and local authorities, the tool's makers have created a centralized, easy-to-sort database that allows researchers to spot trends they otherwise would likely have missed.

"There is a window of opportunity here and an increasing acknowledgement on the part of law enforcement executives that they want to be ahead of the curve and be in control of their data,” says Jack Glaser, a professor of public policy at the University of California, Berkeley’s Goldman School of Public Policy. The problem has been that different jurisdictions keep their own data without offering ways to connect or compare it to other locales, making trends—especially those that go against the conventional wisdom—very difficult to spot. Now criminal justice reform groups are working to aggregate state and local data on key metrics like police stops and use of force incidents. Meanwhile, a group called Measures for Justice recently launched a massive database that houses county-level data on everything that happens after a person has been arrested.

Incarceration Trends is based on jail census and survey data on who exactly is in jail at any given time. Because it dates back to 1970, Kang-Brown says, it gives counties a sense of “what was normal” before the era of mass incarceration. Sometimes it leads to unexpected discoveries—the growth of the rural jail population among them.

“Not surprisingly given the way the media markets operate, most stories have focused on larger metro populations,” says Laurie Garduque, director of justice reform at the MacArthur Foundation, which sponsored the study. “This is sort of an example of something hidden in plain sight.”