The percentage of Americans lacking health insurance has gone down dramatically since the implementation of the Patient Protection and Affordable Care Act, but roughly 10 percent of U.S. adults remain uninsured. Who are they?  

Unsurprisingly, those most likely to lack insurance are the poor, according to a survey by the Urban Institute. The poll found that only 6.6 percent of those with family incomes at or above 400 percent of the federal poverty level (FPL) lacked insurance. Whether those with incomes below the 400 percent threshold had coverage appears to be influenced by whether they live in states that expanded Medicaid under the PPACA. States that did expand guarantee Medicaid coverage to those with incomes up to 138 percent of the FPL.  

The study found that 27.7 percent of those with incomes at or below 138 percent of the FPL lacked insurance in states that had expanded Medicaid. In contrast, only 22.6 percent of Medicaid-eligible individuals in states that chose not to expand Medicaid are uninsured. In many such states that did not expand Medicaid, only those with incomes at or below the FPL are eligible for Medicaid.