Less than half of Americans living with mental illness receive the treatment they need—a failure that lands large numbers of mentally ill people in jails, emergency rooms, and on the streets. One provision of the 2010 Affordable Care Act, a.k.a Obamacare, would help fix the problem. Under the law, states will get hundreds of billions in federal money over the next ten years to provide health care to 2.7 million poor mentally ill people who are currently uninsured. But 17 states—including some states with among the worst mental-health programs in the country—are rejecting these funds.

Here's how it was supposed to work. Obamacare aimed to cover a huge chunk of uninsured mentally ill people by making more Americans eligible for Medicaid, the joint state-federal program that provides health insurance for pregnant women, infants, and people with disabilities. Starting next year, the Affordable Care Act will pay for states to expand Medicaid coverage to all Americans that live on or under 138 percent of the poverty line—$15,856 per year for an individual, or $32,499 for a family of four. About a third of currently uninsured adults who would be able to get health care coverage through this expansion are mentally ill.

In short, the plan was for the federal government to foot the bill for states to provide lots of mentally ill people with health insurance.

But last June, the Supreme Court made the Medicaid expansion section of the Affordable Care Act optional, and Republican governors or legislatures in 17 states have decided to refuse the feds' money, leaving tens of thousands of poor and mentally ill citizens without coverage. Some of the politicians who decided to turn down the extra money cite the added expense (even though the federal government would pick up the entire tab for three years, and then slowly reduce its share to 90 percent). Others object to what they think is overreach by the federal government. Whatever the reason, 1.2 million mentally ill Americans will be left without Medicaid coverage, including 244,272 in Florida, 255,086 in Texas, and 86,058 in Georgia. Some will be able to buy private insurance through the exchanges the federal government is setting up. But people who make less than the federal poverty line would be left out. Here's a map of where those people live:

There's another, deeper problem: Many of the states that turned down the feds' money have some of the worst mental-health systems in the nation: "States deciding not to expand Medicaid are also states that historically have not invested as generously in programs for the most vulnerable individuals," explains Ron Honberg, legal director at the National Alliance on Mental Illness. "There's sort of a consistency there."