Twenty-three states aren’t expanding Medicaid. Here’s who they leave behind.

Twenty-three states are currently not planning to move forward with the Medicaid expansion, which was meant to cover millions of low-income Americans. The population they leave behind is mostly young, minority, single adults, according to two new data briefs from the Kaiser Family Foundation.

Kaiser estimates that approximately 4.8 million people will fall into this no man's land of health-care reform, where they do have the option to purchase private insurance on the individual market -- but would have to do so without any financial help from the government.

Three-quarters of those who will fall into this coverage gap are adults who do not have children. As Kaiser notes, this reflects the limitations on the current Medicaid program. While some states do use the publicly-funded program to cover low-income, single adults, that's the exception rather than the rule. Nine states currently offer coverage to adults, with income limits that range from 10 to 200 percent of the poverty line ($1,1490 to $22,980, respectively).

If there's any silver lining to this data set, it does suggest that those in the Medicaid gap are, from their self-reporting, in better health and potentially in less need of health care. That obviously doesn't protect against catastrophic events that have little to do with an individual's current health. The health-care law was supposed to offer such protection, but -- for these millions of Americans -- now it won't.