State Gun Laws and Mass Shootings – An InDepth Look

Since the year 2000, mass shootings have begun a disturbing trend upwards, in both number of incidents and total casualties according to an FBI report released in September 2014. The report is a study of the active shooter incidents in the United States between the years 2000 and 2013. The report is an excellent read and looks at the trends associated with mass shootings. During a discussion of the topic with a friend of mine, he suggested that it would be interesting to take a look at the occurrence of mass shootings compared with state gun laws, to see if there is any correlation between the two. Challenge accepted.

The first thing that I noticed is that there are a surprising number of states that have never experienced a mass shooting during the time period covered by the FBI report – 11 states, more than one-fifth. Those states are: Alaska, Delaware, Hawaii, Iowa, Maine, Montana, North Dakota, New Hampshire, Rhode Island, South Dakota, and Wyoming. At the other end of the spectrum are California, Florida, and Pennsylvania top the list with 19, 12, and 10 shootings, respectively.

I would be remiss if I didn’t point out that simply looking at total number of mass shootings and/or total number of victims is not a fair way to approach the situation since the population of many states vary widely. So, I have decided to take a look at the problem from a per-capita basis, and to make the numbers easier to compare they are adjusted to be on a per 1,000,000 residents basis.

Gun laws in this country are complicated and to find a way to categorize the laws’ complexities, I found this summary from the NRA. I know the NRA is not exactly a middle of the road organization on this topic, but I found their summary of the laws to be quite unbiased and accurate. The summary is as follows:

Category Title Category Description
No Permit Required State law that allows individuals to carry concealed firearms for lawful purposes without a permit.
Discretionary/Reasonable Issue State law that provides the government with some discretion over the issuance of a carry permit, but which generally grants permits to all law-abiding persons.
Shall Issue State law that provides that, upon completion of specified requirements, a law-abiding person shall be granted a permit to carry concealed firearms.
Rights Restricted – Very Limited Use State law that gives the government complete discretion over the issuance of carry permits, and where that discretion is normally used to deny the issuance of permits.
Rights Infringed – Non Issue State law that completely prohibits carrying firearms for personal protection outside the home or place of business.

One of the best ways to compare a couple of related metrics is to place them on a scatter plot. In the chart below, the total number of deaths per 1 million residents is plotted along the horizontal x-axis and the restrictiveness of the states’ gun laws are plotted along the y-axis, with the more restrictive one toward the top.

Gun Laws vs Mass Shooting Casualties Scatterplot

As you can, see there really is no correlation between the number of deaths from mass shootings and the restrictiveness of state gun laws. This means that there are many more factors at play, and this problem is too complex to solve by legislation alone.

**A note about the calculation for total number of deaths. I summed the number of deaths for each state, then divided by the population figures from the 2010 census and multiplied by 1,000,000 to make the number manageable.

Explore the Data Yourself:

In case you would like to explore the data yourself, I have included an interactive map of the findings:

Data Source: The United States FBI.

Leave a Reply

Your email address will not be published. Required fields are marked *