The United States is the world’s only large wealthy nation that does not provide citizens with universal health coverage. Though the U.S. is home to many of the world’s top hospitals and medical research institutions, there are tens of millions of Americans who do not have health insurance. 

Though the uninsured rate has fallen considerably in the last decade – largely due to provisions of the Affordable Care Act – more than 23 million working age adults lack health insurance. Americans without coverage are less likely to receive preventative care or treatment for chronic conditions – and diseases or accidents that require hospitalization are often financially ruinous. Several studies indicate that almost two-thirds of personal bankruptcies in the nation are due to medical bills that can’t be paid. (Here is a look at the most expensive medical treatments in America.) 

Many Americans receive insurance coverage through their job. Those whose employers do not offer health insurance, and who are not eligible for Medicare or Medicaid, will typically have to pay for insurance out of pocket – and many uninsured Americans cite the high cost of insurance as the reason they go without it. 

Using data from the U.S. Census Bureau, 24/7 Tempo identified the U.S. counties with the worst health insurance coverage. Counties and county equivalents are ranked by the share of the adult population under age 65 who are uninsured. 

Among the counties on this list, uninsured rates range from about 34% to over 50%. For context, 12.3% of the U.S. population between the ages of 19 and 65 are uninsured. 

The vast majority of counties on this list are in states that did not expand Medicaid coverage. Under the ACA, states were offered federal money to extend Medicaid coverage to those with incomes up to 138% of the poverty level. However, 12 states have opted not to expand Medicaid, including Georgia, South Dakota, and Texas – which between them are home to 37 of the 50 counties on this list. Here is a look at America’s best health care system.

Click here to see counties with the worst health care coverage
Click here to read our detailed methodology