The failures in services for people with mental illness and behavioral disorders associated with substance use have resulted in mass incarceration becoming the country’s de facto mental-health-care system. People with mental illnesses in the United States are 10 times more likely to be incarcerated than they are to be hospitalized. Those who don’t end up in prison are likely to cycle repeatedly through patchy psychiatric care, spells of homelessness, and emergency rooms. And every year, about 2 million arrests are made of people with serious mental illnesses.

As a result, the makeup of our prison population tells its own tale: More than 70 percent of people in American jails and prisons have at least one diagnosed mental illness or substance-use disorder, or both. Up to a third of those incarcerated have serious mental illnesses, a much higher rate than is found at large. On any given day, approximately 380,000 people with mental illnesses are in jail or prison across the United States, and another 574,000 are under some form of correctional supervision.

Aside from the human cost, the fiscal impact is astronomical. For example, Miami-Dade County currently spends $636,000 a day—or $232 million a year—to warehouse approximately 2,400 people with mental illnesses in its jail. In shocking contrast, the entire state of Florida spends only $47.3 million annually to provide mental-health services to about 34,000 people in Miami-Dade and Monroe Counties. And this expenditure leaves almost 70,000 people in those counties with no access whatsoever to mental-health services.