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Published: June 3, 2018, 9:16 a.m.

[Content warning: suicide. Thanks to someone on Twitter I forget for alerting me to this question]

Among US states, there\u2019s a clear relationship between gun ownership rates and suicide rates, but not between gun ownership rates and homicide rates:

You might conclude guns increase suicides but not homicides. Then you might predict that the gun-loving US would be an international outlier in suicides but not homicides. In fact, it\u2019s the opposite:

Why should this be?

We\u2019ve\xa0already discussed\xa0why US homicide rates are so high. But why isn\u2019t the suicide rate elevated?

One possibility: suicide methods are fungible. If guns are easily available, you might use a gun; if not, you might overdose, hang yourself, or junp off a bridge. So getting rid of one suicide method or another doesn\u2019t do much.

This sounds plausible, but it\u2019s the opposite of scientific consensus on the subject. See for example\xa0Controlling Access To Suicide Means, which says that \u201crestrictions of access to common means of suicide has lead to lower overall suicide rates, particularly regarding suicide by firearms in USA, detoxification of domestic and motor vehicle gas in England and other countries, toxic pesticides in rural areas, barriers at jumping sites and hanging\u2026\u201d This is particularly brought up in the context of US gun control \u2013 see eg\xa0Suicide, Guns, and Public Policy, which describes \u201cstrong empirical evidence that restriction of access to firearms reduces suicides\u201d.

The state-level data from above support this view \u2013 taking guns away from a state\xa0does\xa0decrease its suicide rate. And then there\u2019s this graph, from\xa0Armed With Reason:

\u2026which shows that adding more guns to a state does not decrease its nonfirearm suicide rate.

But if suicide methods aren\u2019t fungible, then why doesn\u2019t the US have higher suicide rates? Here\u2019s another way of asking this question:

\xa0

The US has fewer nongun suicides than anywhere else. The seemingly obvious explanation is that guns are so common that everyone who wants to commit suicide is using guns, decreasing the non-gun rate. But that contradicts all the nonfungibility evidence above. So the other possibility is that the US ought to have an very low suicide rate, and it\u2019s just all our guns that are bringing us back up to average.

Of all US states, Massachusetts, New Jersey, and Hawaii have the fewest guns. Unsurprisingly, suicides in these states are less likely than average to be committed with firearms. In\xa0MA, the rate is 22%; in\xa0NJ\xa024%; in HI, 20%. Their suicide rates are 8.8, 7.2, and 12.1, respectively. Hawaii has an unusual ethnic composition \u2013 40% Asian and 20% Native Hawaiian, both groups with high suicide rates (see eg the suicide rate for Japan above). So it might be worth taking Massachusetts and New Jersey as examples to look at in more detail.

Either state, if it were independent, would be among the lowest-suicide-rate developed nations. And both\xa0still\xa0have more guns than our comparison countries. If we did a really simple linear extrapolation from New Jersey-level gun control to imagine a state where firearms were as restricted as in Britain, we would expect it to have a suicide rate of around 5 or 6 \u2013 which is around the current level of non-gun US suicides. This is much lower than any of the large comparison countries in the graph above, but there are two developed countries currently around this level \u2013 Italy and Israel. I think it makes sense to suppose that the US might have a low Italy/Israel-style base rate of suicides.

For one thing, it\u2019s unusually religious for a developed country. Religion is one of the strongest\xa0protective factorsagainst suicide. This also seems like a good explanation for Italy and Israel.

For another, it\u2019s culturally similar to Britain, which also has a low suicide rate somewhere in the 7s. Other British colonies don\u2019t seem to have kept this effect \u2013 Australia and Canada are both higher \u2013 but maybe the US did.

And for another, it\u2019s unusually ethnically diverse. Blacks and Hispanics have\xa0only about half\xa0the suicide rate of whites; which means you would expect the US to be less suicidal than Europe. I previously believed this was because whites had more guns, but this doesn\u2019t seem to be true:\xa0Riddell et al\xa0find that whites have higher non-firearm suicide rates too. So this could be an additional factor driving US rates down.