States that run their own Affordable Care Act insurance market­places significantly outperformed the rest of the country in attracting consumers to sign up for health plans for 2018, according to enrollment tallies released Wednesday.

Overall enrollment stayed essentially level from the year before in the 11 states plus the District with state-based marketplaces, while sign-ups in states that rely on the ACA’s federal exchange fell, on average, by more than 5 percent. Five states with hybrid systems did best of all, according to a report compiled by the National Academy for State Health Policy.

The data show that, nationwide, almost 11.8 million Americans chose ACA health plans for this year. The total is nearly a half-million fewer than for 2017 and about 900,000 fewer than in 2016, the high point in the five years since the marketplaces created under the law began selling coverage to consumers who lack access to affordable health benefits through a job. But the modest decline is well short of the enrollment meltdown that many supporters and foes of the ACA had anticipated.

The report is the first full portrait of the results of an enrollment season hampered by steps the Trump administration has taken to undercut the insurance marketplaces and unsuccessful efforts last year by congressional Republicans to dismantle large parts of the sprawling health-care law.

Against such head winds, leaders of state insurance exchanges and other health policy experts characterized the ultimate enrollment as surprisingly resilient. “The message is, people want coverage, and they came and got it,” said Trish Riley, the health policy group’s executive director.

In contrast with repeated assertions by President Trump that the ACA marketplaces are essentially dead, “it’s not collapse, it’s incredible stability,” said Peter Lee, executive director of Covered California, the nation’s second-largest exchange after Florida.


ACA Chart (The Washington Post/The Washington Post)

Enrollment in Florida, which relies on the federal marketplace, fell 2.5 percent from 2017. Despite an intense, well-funded campaign urging people to sign up, California’s marketplace enrollment dipped by roughly the same amount. Lee attributed that largely to the fact that his exchange encouraged people with incomes too high for federal premium subsidies to seek coverage outside the ACA marketplace. For the most popular level of coverage, those off-markeplace plans ended up being less expansive than identical ones in the exchange after the White House ended important funding to participating insurers in the fall.

Even so, the number of Californians buying marketplace coverage for the first time rose 3 percent from the year before — a sign of strength, Lee said.

Among the 12 state-based marketplaces, enrollment rose in eight. It also rose in three of the five states that run their own marketplaces but rely on the federal HealthCare.gov computer system.

In contrast, 2018 sign-ups increased in just five of the 34 states that are part of the federal marketplace.

In a conference call for reporters Wednesday, leaders of several state marketplaces said theirs tended to fare better for a combination of reasons. In states using the federal exchange, the enrollment season was shortened to six weeks, while many states with their own marketplaces continued their sign-up period for two or three months. And though federal money was sharply curtailed for advertising and other outreach activities, some state exchanges had robust programs and well-staffed call centers to encourage sign-ups.

“The local flexibility makes all the difference,” said Pam MacEwan, chief executive of Washington state’s Health Benefit Exchange, which had an 8 percent surge in customers selecting health plans for this year.

But the exchange directors said that daunting obstacles loom for the 2019 enrollment season scheduled to begin in November. “There have been several shots that have been fired at the individual market” by the administration and Congress, MacEwan said.

One of the most significant is a part of the new federal tax law that next year will eliminate penalties for individuals who flout the ACA’s requirement that most people carry insurance. Another is the cost-sharing reduction subsidies to insurers that Trump ended in October.

Next year “looks very troubling,” Lee said, citing estimates that ending enforcement of the insurance mandate could drive up ACA health plans’ premiums by 15 percent to 30 percent. He and the others urged Congress to give states money for “reinsurance” programs that can help buffer the burden of especially high-cost customers — “so we don’t have a train wreck in 2019,” Lee said.

Zachary Sherman, director of Rhode Island’s HealthSource, said his state has analyzed the effect there of ending enforcement of the insurance mandate and predicts that premiums for marketplace health plans will soar by an average of 50 percent in the next three years. “That is something that scares us quite a bit,” he said.

The data in Wednesday’s report are based on the most recent “enrollment snapshot” that the Health and Human Services Department released in December for the federal-exchange states, plus final tallies from state-run marketplaces. States are reporting those tallies to HHS for a government enrollment report due out next month.