A health insurer has agreed to sell Affordable Care Act health plans next year in a rural Ohio county, filling in the nation’s last potential bare patch in the marketplaces created under the law.

The announcement on Thursday by Ohio insurance officials means that, at least for now, there will be no places in the United States where eligible Americans will lack access to subsidized ACA health coverage for 2018 when the next annual enrollment period opens in November.

Although insurers could still defect in the next month, before they must sign federal contracts to sell ACA coverage for the coming year, the move by CareSource to sell marketplace health plans in Paulding County, on the western edge of Ohio, appears to end a recent scramble by officials in seven states to persuade insurance companies to participate in a total of 81 counties.

Those potential bare spots emerged mainly as large, nationwide insurers have withdrawn from all or most of the ACA marketplaces they once served — a result of sicker and more expensive customers than they had expected and uncertainties bred by Republican efforts to overturn much of the 2010 health-care law.

The hopscotching to ensure that every county has at least one company selling ACA health plans has been more widespread than a year ago, when the residents of only one Arizona county were temporarily at risk of lacking access to such coverage.

Even with the bare spots filled at the moment, nearly 1 in 3 people who have ACA health plans will find only one insurer selling such coverage in their area, according to federal figures — more than at any time since the marketplaces began four years ago.

Still, filling the gap in the last county — a rural area with 334 current ACA customers — was greeted Thursday as a milestone signaling that the exchanges that are a core aspect of the ACA are withstanding the political feuding over the law’s future. “The marketplaces have proven to be remarkably resilient and just refuse to fail,” said Larry Levitt, senior vice president of the Kaiser Family Foundation.

That interpretation differs from that of the Trump administration. For months, the president and his top aides have said that the ACA exchanges have collapsed and are beyond repair. Since late spring, the Health and Human Services Department has issued maps showing the counties that, at a given time, had no ACA insurer lined up for 2018 — or just one. Accompanying the first map in early June, when 47 counties were projected to have no ACA coverage, was a statement by Seema Verma, administrator of HHS’s Centers for Medicare and Medicaid Services, that said: “This is yet another failing report card for the exchanges.”

Administration officials did not soften their position Thursday, as the last gap was closed. “Premiums continue to surge, insurers continue to abandon wide swaths of the country, and choices continue to vanish,” said Matt Lloyd, a senior HHS spokesman. “Nearly half of counties across the nation only have one health insurance option which, by definition, is not a choice. Under Obamacare, Americans were promised access to a wide variety of high-quality, affordable coverage options.”

Like 14 counties in Nevada that were filled with ACA insurers last week and other areas that have had difficulty attracting insurers, Ohio’s Paulding County is rural.

Pamela Morris, president and chief executive of CareSource, said that the insurer had agreed last month to fill ACA coverage holes in eight of 20 Ohio counties that were bare at the time. She said it did not initially reach into Paulding because providers of care were scarce and many residents seek health care in nearby Indiana.

In the end, she said, it was able to cobble together the provider networks the ACA requires by combining with an adjacent Indiana county.

CareSource plans next year to sell ACA health plans in 59 counties in Ohio and 79 in Indiana. Like another insurer, Centene, that also has stepped into bare counties in some states, CareSource has focused in the past on providing managed care to low-income people on Medicaid.

Morris said that Ohio’s insurance officials “were incredibly anxious to get this accomplished . . . We are delighted to be able to do this.”