When Christie Green took her job three years ago as public-health director for the Cumberland Valley District in southeastern Kentucky, she had nearly two decades of experience in the state’s public-health system.

But Green still wasn’t prepared for what she saw when her predecessor took her around this hardscrabble swathe of Appalachia centered on Clay County, which The New York Times once described as the hardest place in the United States to live. “In the first week,” Green recently told me, “I met more people who were raising their grandchildren than I had in my entire career before that.”

The missing generation in those families is a grim measure of how the opioid epidemic has torn through economically struggling rural counties like a tornado, breaking lives as if they were so many tree limbs. From Green’s perspective, the storm is still intensifying. “I don’t think it has peaked, unfortunately,” she said.

Clay County is typical of the places hit hardest by the opioid crisis. It is preponderantly white (93 percent), with very few college graduates (just 10 percent), and it voted overwhelmingly for Donald Trump (who carried 87 percent of its vote). Another thing about Clay County is typical, too: As it grapples with the opioid epidemic, it is increasingly relying on Medicaid, which covers fully 44 percent of the population.

As Senate Republicans resume their drive this week to repeal former President Barack Obama’s Affordable Care Act, one of their principal obstacles is resistance from GOP senators and governors in states that expanded Medicaid under the law. And one of the principal reasons for that opposition is Medicaid’s central role in responding to the opioid challenge. Federal data show that Medicaid now pays for about one-fourth of all substance-abuse treatment, up from about one-tenth in 1986. “Losing expanded Medicaid coverage would absolutely hamstring our operations to address opioid addiction in eastern Kentucky,” Green said. “We are critically dependent on that.”

New data compiled by the Center on Budget and Policy Priorities, and provided exclusively to The Atlantic, underscores just how important Medicaid is for many of the places struggling most with opioids.

The CBPP, a liberal research and advocacy group, analyzed Centers for Disease Control and Prevention data on overdose deaths per capita in the counties of four heartland states confronting the opioid crisis: Kentucky, West Virginia, Ohio, and Arkansas. Then it used Census data to measure what share of each county’s population receives health care through Medicaid. The results were striking.

Looking at the 10 counties in Ohio with the highest rates of overdose deaths, Medicaid provides coverage for one-fourth or more of the population in five of them, and about one-fifth in the remaining five. In Arkansas, Medicaid covers about three-tenths of the population in the county with the highest rate of overdose deaths, and between one-fifth and one-fourth in the other nine.

In West Virginia, Medicaid covers more than 30 percent of the population in three of the 10 hardest-hit counties, over one-fourth in five more, and at least one-fifth in the final two. In Kentucky, 17 counties tie for the highest rate of overdose deaths. There, Medicaid covers over two-fifths of the population in five counties and roughly one-third in all the others.

Colleen Grogan, a University of Chicago health-policy professor, notes that Medicaid has become indispensable in these counties for two reasons. First, she said, the ACA extended Medicaid eligibility, for the first time, to low-income working adults: They “never had access to coverage—and many of those people had substance-abuse problems.” Equally important, the ACA required states joining the Medicaid expansion to cover drug treatment.

Like Clay in Kentucky, the counties with the highest overdose rates across the four states are predominantly white and have very few college graduates. Most face economic strain. Last year, Trump carried every one of the highest-overdose counties in each of the four states examined. In fact, Trump won over 60 percent of the vote in all 47 counties except two in Ohio.

That means these areas of the heartland that lean most on Medicaid to contain the opioid epidemic—which the president himself pledged to eradicate—are firmly Trump country. Yet under both the House and Senate bills, Medicaid coverage would plummet in Kentucky, Arkansas, West Virginia, and Ohio, the Urban Institute has projected.

Senate Republicans have proposed compensating for that loss with a 10-year, $45 billion fund specifically to fund opioid services. Experts argue that’s not nearly enough to meet the need. But they also note that even if the money were sufficient, replacing Medicaid coverage with new grants for clinics would pose a problem—by resegregating drug-abuse treatment precisely as providers are succeeding in integrating it into the full range of mental and physical health services. “These grants won’t be as effective or efficient as comprehensive health coverage,” said Matt Salo, executive director of the bipartisan National Association of Medicaid Directors. Besides, as Green said, addicts—“beyond a shadow of a doubt”—are more likely to seek treatment if they have insurance that will fund it. “It is 100 percent out of their [financial] range if they aren’t covered,” she said.

Given the consequences of slashing Medicaid coverage, the Senate’s proposed opioid fund resembles little more than a fig leaf. It is far too modest to hide the explicit truth that the House and Senate’s Medicaid cuts would devastate exactly the drug-ravaged communities that placed more faith in Donald Trump last November than almost any others in America.