WASHINGTON — President Obama’s health care law has become a tale of two Americas.
States that fully embraced the law’s coverage expansion are experiencing a significant drop in the number of uninsured residents, according to a new survey released Tuesday. States whose leaders still object to the measure are seeing much less change.
The Gallup-Healthways Well-Being Index found an overall drop of 4 percentage points in the share of uninsured residents for states accepting the law’s core coverage provisions. Those are states that expanded their Medicaid programs and also built or took an active role managing new online insurance markets.
The drop was about half that level, 2.2 percentage points, in states that took neither of those steps, or just one.
‘‘Those states that implement the law’s major mechanisms are seeing a significantly greater decline in their uninsured rates,’’ said Dan Witters, research director for the poll.
Medicaid expansion mainly helps low-income uninsured adults in states accepting it. Insurance exchanges operate in every state, offering taxpayer-subsidized private coverage to people who have no health plan on the job.
Leading the nation were two southern states where the law has found political support. Arkansas saw a drop of about 10 percentage points in its share of uninsured residents, from 22.5 percent in 2013, to 12.4 percent by the middle of this year.
Kentucky experienced a drop of nearly 9 percentage points, from 20.4 percent of its residents uninsured in 2013, to 11.9 percent.
Although the poll’s margin of sampling error is higher for smaller states, Witters said Gallup has a high level of confidence that the numbers represent real changes.
The poll found contrasts among states that share a border, but have taken different paths politically.
■ While Arkansas had the 10-point decline in its uninsured rate, the drop in Tennessee was 2.4 percentage points.
■ The uninsured rate in West Virginia fell 5.7 points after the state agreed to Medicaid expansion, but there was no change for neighboring Virginia, where Governor Terry McAuliffe, a Democrat who has been blocked by a Republican-led Legislature.