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To see what I mean, just compare Tennessee with its neighbor Kentucky. As recently as 2013, just before the Affordable Care Act went into full effect, the two states looked similar in terms of health care: In both states, about 20 percent of nonelderly adults lacked insurance. But unlike Tennessee, Kentucky did expand Medicaid, and it also did its best to make Obamacare work.

The result was a two-thirds drop in the uninsurance rate. At the same time, progress in Tennessee was far more limited. At this point, adults in Tennessee are twice as likely as their neighbors to lack health insurance.

And the divergence in destinies was even greater for rural residents. According to a Georgetown University study that covered a seven-year period spanning the introduction of the A.C.A., the percentage of low-income rural adults without health insurance fell 27 points in Kentucky, only six points in Tennessee.

Of course, if the U.S. were like every other wealthy nation, and provided some kind of universal health care, there would be no uninsured at all. Those heart-rending scenes in Cleveland would be inconceivable anywhere else in the advanced world. But the A.C.A. isn’t a future aspiration, it’s an already-existing program — and a lot of rural America’s medical misery could be avoided if states like Tennessee were willing to take advantage of that program.

And we’re not just talking about having insurance; we’re talking about whether there are doctors and hospitals available to provide care. True, rural hospitals have been closing in many states as the nonmetropolitan population declines. But a project that tracks rural hospital closings since 2010 finds that a great majority have taken place in states that didn’t expand Medicaid. Four rural hospitals have closed in California, but 17 have closed in Texas. Tennessee has had three times as many closings as Kentucky.