In Southern states in the U.S. that expanded their Medicaid programs under the Affordable Care Act, adults experienced low rates of decline in both physical and mental health compared with adults living in states that did not opt for Medicaid expansion.

That’s the finding of a new study published this month in the journal Health Affairs. The study, conducted by researchers at Vanderbilt University School of Medicine and Harvard Medical School, could create new incentives in the 14 states that have not expanded Medicaid to do so.

The new research draws on data on 15,536 low-income individuals recruited primarily at community health centers in 12 Southern states as part of the Southern Community Cohort Study. Researchers found that Medicaid expansion reduced the likelihood of low-income adults experiencing a self-reported health status decline, particularly for adults with severe mental and physical limitations.

Researchers sought to learn whether the safety net in non-expansion states is good enough to provide access to health care for poor Americans. They found that actual health coverage, such as Medicaid, is better.

“These findings suggest that access to safety net providers in Southern states is an inadequate substitute for health insurance coverage,” the Harvard and Vanderbilt researchers, led by Vanderbilt’s John Graves, wrote in Health Affairs. “Thus, nonexpanding Southern states could improve the health of their low-income residents by accepting expansion funds or otherwise extending coverage to low-income residents.”

This research is consistent with a survey of over 300 Medicaid expansion studies from 2014-2019 compiled by the Kaiser Family Foundation, which found greater access to treatment and better health outcomes overall, including fewer deaths.

Four Southern states – Florida, Mississippi, Missouri and Oklahoma – have not opted for Medicaid expansion but recently have debated doing so. Expansion efforts in Florida and Mississippi for now are stymied, but Oklahoma voters this November will vote on a ballot measure on whether to expand, and voters in Missouri are expected to do likewise, although the Missouri initiative has not yet qualified for the ballot.

Interestingly, of the last five states to expand Medicaid, four did so at the ballot box, bypassing either Republican legislators or Republican governors or both – Idaho, Maine, Nebraska, and Utah. (In Virginia, the fifth most recent state to expand Medicaid, new Democratic legislators added to a bipartisan base of support provided the winning margin to expand Medicaid.)

“Study after study has shown the same thing—people in states with Medicaid expansion are better off,” Jonathan Schleifer, executive director of The Fairness Project, told Forbes. “Americans get it, and they’re tired of politicians valuing special interests over the lives of their own constituents. That’s why we’ve seen a revolt at the ballot box on this issue in even the deepest of red states.”

Schleifer, whose organization has raised and provided substantial funding to support the Medicaid ballot initiatives, said access to health care is an issue Americans take seriously.

“People want to keep rural hospitals open and ensure that their friends and family can see a doctor no matter where they live,” he said. “That was true in Maine, Idaho, Utah and Nebraska in 2017 and 2018, and it has been true in Oklahoma and Missouri this election cycle.”

Go here to read more about efforts to expand Medicaid at the state level.