When the Affordable Care Act took effect in October 2013, there were 14 states in which more than 1 in 5 adults lacked health insurance; today only Texas remains, according to data released Monday.
At the other end of the scale, only five states' populations were so well-insured in 2013 that fewer than 1 in 10 adult residents lacked insurance. Today, more than half the states have achieved that goal.
The state-by-state insurance levels, which detail how rapidly the insurance picture has changed since President Obama's signature healthcare reform started, come from a large-scale, twice-a-year survey by Gallup. The survey included more than 178,000 adults in 2013, before the law took effect, and 88,667 in the first half of 2015, allowing unusually precise estimates of the effect the law has had at the state level.
Texas, whose officials have strongly resisted cooperation with the new law, had the highest level of residents lacking insurance before the law took effect and has made among the least progress of any state. Its uninsurance rate fell from 27% in 2013 to just under 21% in the first half of this year, making it the only state that has more than one-fifth of its residents uninsured.
By contrast, in Arkansas and Kentucky, both of which started above 20% uninsured, just 9% of adult residents lack insurance.
California has gone from just under 22% without insurance to just under 12%, experiencing the largest number of newly insured people in the country.
In addition to Texas, most of the states with the highest levels of adults lacking insurance are located in the South and interior West in states including Idaho, Montana, Wyoming and Nevada.
By contrast, most of the New England states have 5% or fewer of their residents uninsured, a mark also achieved by Iowa, Minnesota and Hawaii.
The Obamacare law has two main ways of insuring people who do not get health coverage at their jobs. People can sign up to buy insurance through the law's online marketplaces and receive government help with the cost if their incomes are below around $97,000 for a family of four. Those whose incomes are too low to buy insurance on the exchanges can qualify for Medicaid.
About half the states have expanded Medicaid under the law. Most of the states that continue to have high levels of uninsured residents have declined Medicaid expansion, which many Republican governors and state legislators oppose.
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