For years, African Americans have been disproportionately targeted by the criminal-justice system, and have been sent to jail and prison in disproportionate numbers. But that disparity has undergone a subtle shift in recent years: A striking data analysis by the Vera Institute suggests a shift in the racial dynamics and geography of jail over the past two decades. The number of white people in jail has soared over the past two decades, the analysis found, while the black jail population has steadily declined. According to the analysis, “white jail incarceration rates have steadily grown across all regions and jurisdiction types since 1990,” particularly small and medium-sized metropolitan and rural areas.

Despite an overall reduction in the prison population in the past few years, whites are increasingly coming into contact with the criminal-justice system, and a lot of that can be traced to one source: the opioid epidemic. After years of drug policies that dealt harsh punishment to marginalized communities, civil-rights groups and political officials have succeeded in reining in some of the toughest criminal-justice policies and promoted alternatives to incarceration. Yet just as those structural changes were showing progress, a rising jail rate in poor white towns has underscored the structural segregation and instability that continue to drive criminalization and imprisonment in long-overlooked regions. There has meanwhile been a parallel drop in black jail incarceration in large and medium-sized cities, and urban and suburban metro areas.

So are white people replacing blacks behind bars? Clearly, no: Blacks are still jailed at approximately 3.6 times the rate of whites. But the rise in white jail populations, clustered in once-stable small towns, is remarkable. The trend has been exacerbated by a lack of non–criminal justice alternatives for dealing with opioid addiction issues, particularly a lack of adequate treatment programs and a climate of systematic social alienation, joblessness, and instability plaguing blue-collar communities.

Since 1990, white jail incarceration rates have risen by nearly 90 percent, from some 163,500 to 330,300 people. Outlying, often isolated communities are where jail populations have swelled most markedly. In rural towns, specifically, white incarceration jumped by 165 percent, nearly double the rate in small metro areas. As of 2013, rural areas held 15 percent of the general population but one fifth of the jail population, or about 146,000 people (the largest share of the jail population still lies in small towns and cities, with a quarter-million people).

Although the lack of rehabilitative and community-oriented alternatives to incarceration may be hitting whites hardest in some communities, the new demography of American jails seems to mark a carbon-copy of the zero-tolerance, authoritarian law-enforcement tactics earlier deployed to police communities of color. In other words, criminal-justice strategies centered on dehumanization and punishment can be pivoted against any marginalized population, and the structural biases of a system previously used to arrest and imprison blacks are now increasingly targeted at largely white communities caught up in the opioid crisis.

The public-health crisis has set off an explosion in the market for street heroin and other drugs, leading to a sharp increase in opioid-related crime and arrests nationwide. According to the analysis, “white people [have] accounted for nearly 90 percent of new opioid users between 2000 and 2010, and suffered 82 percent of all opioid-related overdoses in 2015.” The rise in incarceration that has coincided with the opioid epidemic was not inevitable; it has stemmed from a lack of treatment-based alternatives, as well as outmoded, punitive sentencing practices. Some towns and smaller cities may not have adopted the progressive reforms that larger cities have undergone in recent years to curb mass incarceration, such as shifting away from heavy-handed, zero-tolerance police tactics. So in New York, ending the practice of “stop and frisk” helped curb the mass arrest and jailing of young youth of color. But in rural Rust Belt towns, opioid users might end up getting warehoused in the county jail simply because there’s no nearby treatment facility.

Bell County, Kentucky, home to one of the worst opioid-related-death rates in the country, is a sad example of the clash between the criminal-justice system and the opioid crisis: The community’s jail population has surged alongside the abuse of prescription drugs. Today, according to local officials, “trafficking in prescription drugs and methamphetamines—as well as crimes related to drugs, like theft—are the leading reasons for incarceration. The county of approximately 27,000 people spends over a million dollars annually on its jail.” Since 2015, the predominantly white region has seen a doubling of whites in jail but a three-quarter drop in the black population in jail.

But the statistics on who exactly is being jailed and why remains murky due to the lack of systematic data collection. In fact, the white jail rates could be distorted by miscategorization of Latinos as whites (though it should be noted that the Latino incarceration rate has also climbed under the same harsh criminal-justice policies).

Likewise, we know little about the gender or age disparities within these trends, though it’s evident that, around the country, female incarceration is on the rise, and there’s been an uptick in the number of teens housed in adult jails in recent years (the Vera Institute points out that “Some jurisdictions allow 17-year-olds in adult jails,” which is both socially and legally damaging for youth).

Nonetheless, despite the diverging trend lines in jails, black people remain disproportionately punished at every level of the criminal-justice system. At the same time, while the reason people are getting put behind bars might differ for blacks and whites, problems with inequality and lack of social supports that keep people imprisoned are universal and cut across racial lines. As Vera Institute researchers explain, “differences in the distribution of various criminal justice resources—from access to courts, to availability of pretrial, treatment, or public defender services—are resulting in different racial outcomes depending on where people live.”

Whether in the big city or small-town America, there’s no justification for locking anyone up when society could be providing them rehabilitation and humane treatment. Now we see that the patterns of racial disparity can be as arbitrary and unpredictable as any other factor in the system—another sign that the fundamental unfairness of America’s jails hurts us all.