From the NYT: Millions of Poor Are Left Uncovered by Health Law

One part of the ACA encourages states to provide access to health care to the poor by expanding Medicaid. As opposed to Medicare - which is a fully federally run program that provides medical assistance for the elderly - Medicaid is funded by the national government but run largely by the states. This allows the states some control over who gets funding and who does not.

Originally the ACA required states to expand coverage to people with incomes up to 133% of the federal poverty level or risk losing all Medicaid funding. This was the only major part of the ACA that was found unconstitutional. States were allowed to be able to opt out of the expansion while still retaining existing benefits.

Many states, including Texas, have done so.

The NYT discusses the consequence of this decision, which had created a group of 8 million or so people a bit too wealthy to qualify for Medicaid, but not wealthy enough to qualify for subsidies for health insurance.

Click here for a map showing where the poor and uninsured live.

The Dish flags this chart showing Medicaid eligibility levels in different states and whether that state has accepted Medicaid expansion.