Later this year, residents of Pinal County, Arizona, who goshopping for health insurance under Obamacare will face a peculiardilemma -- they’ll have to buy a product that may not exist.

Related: Humana reduces exchange sales

The 400,000-population county southeast of Phoenixcurrently doesn’t have a single health insurer offering coveragenext year on the Affordable Care Act’s exchanges, where Americanscan shop for the insurance they’re required to have under the law.With the impending pullout of major health insurers -- includingAetna Inc., UnitedHealth Group Inc., and Humana Inc. -- PinalCounty is just one place around the country where Americans will beleft with few, if any, choices for coverage.

“The idea was that people who use the exchanges would have avariety of plans by different carriers,” said Robert Blendon, ahealth-policy professor at Harvard University’s T.H. Chan School ofPublic Health. “If it isn’t addressed, you will have more companiesdrop out and you’ll have more pressure on the other companies interms of their potential losses.”

The dropouts also undermine a key promise of the law: multipleinsurers would compete for consumers’ business each year, and thepower of the market would control costs and raise quality. Instead,the opposite is happening. Rates may jump 24 percent next year,according to ACASignups.net, a website that tracks the law, and aquarter of U.S. counties could have just one insurer on theexchanges, according to Cynthia Cox, a researcher at the KaiserFamily Foundation.

Few choices in many places

It wasn’t always so in Arizona. When the ACA began offeringcoverage three years ago, the state’s consumers had eight healthinsurers to pick from, said Swapna Reddy, a clinical assistantprofessor at Arizona State University’s School for the Science ofHealth Care Delivery. In about half the state’s counties, they’renow down to one.

Related: Obamacare is in trouble as insurers tire of losingmoney

“Many insurers offered premiums that were too low from thebeginning, and they weren’t sustainable,” she said in an interview.“Unfortunately, we might be living through the one-time correction,but hopefully it’s not all doom and gloom.”

In Pinal County, two insurers, Blue Cross Blue Shield of Arizonaand UnitedHealth, offered ACA health plans this year. UnitedHealthis leaving and BCBS previously said it would limit its statefootprint. Aetna had initially planned to jump into the countybefore deciding to exit the state entirely.

While the law requires everyone to have coverage, people inPinal County probably wouldn’t face a penalty for being uninsured.The Affordable Care Act contains an exemption to financialpenalties if there’s not an affordable option on the exchanges.

Unstable market

“Arizona is now an example of what happens when the market isunstable, leaving residents with little choice,” Blue Cross BlueShield of Arizona said in an e-mailed statement. The not-for-profitinsurer said it’s re-evaluating its coverage next year because ofthe Aetna pull-out.

Related: Aetna to quit most Obamacare markets, joining majorinsurers

While consumers can buy insurance outside the exchanges, theywon’t be eligible for the government-provided tax subsidiesspecifically targeted to help lower-income people afford it. Theaverage subsidy in Arizona this year is $230 a month, and more thantwo thirds of people on the state’s exchange qualified.

Not just Arizona

It’s not just Pinal County. Entire states such as South Carolinaand Alabama may be down to one insurance option on the Obamacareexchanges, though regulators are still reviewing 2017 filings.Parts of other states, including Georgia and North Carolina, may beleft with a single carrier as well.

Aetna announced its intention to pull out of 11 of the 15 stateswhere it sells individual Obamacare plans on the exchanges onMonday, after earlier saying it faced $300 million in projectedlosses this year. UnitedHealth and Humana also said the high costof caring for sick customers helped push them from the market.

Those exits by three of the country’s biggest health insurersmean that more than 2 million people may have to pick new plans for2017, according to a Credit Suisse Group AG estimate. In addition,16 of the 23 health insurance “co-ops” -- federally financed,not-for-profit insurance startups -- have gone out of business,including four this year, further reducing consumers’ choices. Sixof the seven remaining are facing financial difficulties.

More states

In South Carolina, the ACA hasn’t worked for insurance companiesor consumers, said Ray Farmer, the state’s insurance regulator.

“We have fairly narrow networks at high costs, and companiescannot seem to make a profit,” he said. “I’m not so sure this iswhat the federal government contemplated with their program.”

Up the coast in North Carolina, Insurance Commissioner WayneGoodwin said the news of Aetna’s withdraw caught him by surprise,and that he learned of it while reviewing Aetna’s proposed ratesfor next year.

“I am shocked and disappointed that Aetna and its executiveshave chosen to
abandon their exchange members,” he said in an e-mailed statement.“Never during the review did the company indicate any concern” thatcouldn’t be resolved.

Aetna declined to comment on Goodwin’s remarks.

Other options?

BlueCross BlueShield of North Carolina, a not-for-profit, hasn’tsaid whether it will remain in every county for 2017, where it’sthe only option in some places. The insurer says it’s evaluatingthe effects of Aetna’s exit -- UnitedHealth earlier quit NorthCarolina as well -- and what rates regulators will let itcharge.

Related: What does UnitedHealth's PPACA exitmean?

“We have not made a final decision of our continuedparticipation until the answers to these questions are known,” theinsurer said in a statement.

It’s also not clear yet what, if anything, the U.S. governmentcan do in places where the are no insurers selling coverage on theexchanges, but the health law requires people to buy it or pay afine.

The U.S. Department of Health & Human Services is workingwith Arizona regulators to ensure that everyone in the state hasaccess to health coverage, according to Ben Wakana, an HHSspokesman.

Stephen Briggs, a spokesman for the Arizona regulators, says thestate can’t force insurers to offer coverage on the exchange.“We’re doing everything within the law, within our authority,” hesaid.

Nor can they stop them from leaving, said Joe Antos, a healtheconomist at the American Enterprise Institute, aconservative-leaning think tank in Washington.

"Unless there is a change in the law, conditions aren’t going tochange,” Antos said. The insurers are “basically saying, ‘If thisis the way it’s got to be, we have to leave.’"

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