What one thing do Congress, the National Rifle Association, and the general public all overwhelmingly agree on? Mental illness is largely responsible for gun violence.

Much of the discussion around gun violence in Congress in the aftermath of last year’s mass shooting at an elementary school in Newtown, Conn., focused on mental-health care in addition to stricter gun-control measures, though legislation addressing any of this failed to pass.

A Gallup Poll from September showed that 80 percent of Americans think mass shootings are the fault of a lousy mental-health care system that fails to identify at-risk individuals.

The National Rifle Assocation proudly proclaimed in a fact sheet earlier this year, “Since 1966, the National Rifle Association has urged the federal government to address the problem of mental illness and violence.”

And since 1966, the National Rifle Association has been trying to associate two things that in reality have relatively little to do with one another. But to be fair, the general public and politicians are just as guilty.

Do mental-health care facilities need substantial improvement? Absolutely. Will improving access to mental-health care lead to a noticeable reduction in violent crime? Not likely.

That’s not to say some forms of mental illness don’t make people more likely to commit violent acts, but only some extreme mental illnesses are dangerous. A 1994 study by the National Institute of Mental Health found that people suffering from serious mental illness (schizophrenia, bipolar disorder, major depression, etc.) were around two to three times more likely than people without mental illness to commit assault.

However, such illnesses are extremely rare, which is why an estimated 3 to 5 percent of violent crime is attributed to the mentally ill, according to the New England Journal of Medicine. It also reported that “people with no mental disorder who abuse alcohol or drugs are nearly seven times as likely as those without substance abuse to report violent behavior.”

Not only are the mentally ill responsible for proportionally little violent crime, the ones who have extremely serious mental-health problems are actually less violent than alcoholics and drug addicts.

Most Americans would probably be surprised to learn that almost half of them will suffer from a mental disorder at some point in their lives, according to a 2011 report by the U.S. Centers for Disease Control and Prevention. The most common of these include anxiety and mood-related illnesses.

The quality of mental-health care must improve, not because it will reduce violence but because so many Americans suffer from mental illnesses.

In spite of the prevalence of mental illness, state governments cut $1.8 billion from their budgets between 2009 and 2011, the National Alliance on Mental Illness reported. Clinics closed, swaths of staffers were laid off, and many seriously ill patients lost access to essential services.

Worse yet, people with serious mental illnesses are more than three times more likely to end up in prison than a mental-health facility. In only a few states, such as Minnesota and Maine, are those with major mental illnesses about equally likely to go to a hospital as a prison that is an injustice in itself.

Mental illness is a serious problem, but improving services to treat these forms of sickness won’t necessarily mean any fewer Americans will die as a result of gun violence. With nearly half of the U.S. population expected to suffer from mental illnesses in their lives, that in itself is enough reason to improve funding and access to mental-health care.