How many school shootings since Columbine?

Numbers since April 1999 can range from 8 to 2,032 depending how you define "school shooting". Reduce bias by looking at many different ways to filter the data.

There is no legal definition of ‘school shooting’ which means that each reporter writing a 25 years after Columbine story this week is making a personal decision about how to frame the issue.

Let’s start with a different question: How many coffee shops are in a town?

This might seem like a simple query, but it hinges on how you define a coffee shop. Would you include:

• McDonalds that sells coffee? What about McCafe with a special coffee menu?

• Dunkin Donuts? It’s more like McDonalds than Starbucks.

• Gas stations with coffee pots? What about truck stops with full service cafes?

• Food trucks that sell breakfast tacos and lattes?

What really drives the definition of a coffee shop is what the person asking the question wants to know. Each of these people would be looking for a different answer:

• Gas station owner thinking about expanding hot beverage selection.

• Real estate developer considering locations for a new mixed-use development.

• Business growth manager of a mid-sized artisan coffee shop looking for locations without competitors.

• Remote worker looking for a place that sells coffee to work at for 3-4 hours.

• Tired driver on a highway at midnight looking for a place that is open and sells coffee.

To each of these people, a standardized definition of a coffee shop isn’t very useful. How you define something really depends on what you want to know.

Telling Data Stories

A spreadsheet of data has no story. It’s always a choice by the data analyst to shape how the numbers are presented.

The simplest ways to measure data are the mean, median, and mode. If you look at data from the number of victims at 10 school shootings, each measure tells a different story. Assume the number of victims for these 10 school shootings is 0, 1, 1, 1, 1, 2, 2, 4, 12, and 70.

• Mean = 9.4 victims

• Median = 1.5 victims

• Mode = 1 victim

If you say that on average 9 victims are shot at a school, this is correct but needs further clarification that most often two or fewer victims are shot. Alternately, saying that only that one person shot is the most frequent situation leaves out the extreme severity of the incidents with 12 and 70 victims.

Each of these measures is a valid way to represent the data and they each tell a very different story. The only way to really understand a problem is to either look at the raw data to form your own conclusions or look at multiple different ways the data is presented.

Any shooting on school property since Columbine: 2,032 school shootings

The K-12 School Shooting Database uses a widely inclusive definition that documents when a gun is fired, brandished (pointed at a person with intent), or bullet hits school property, regardless of the number of victims, time, day, or reason.

The purpose of this definition is to collect as much information is possible so that other researchers can filter it to answer a wide array of research questions.

Here are some examples of ways to filter the data to tell different stories.

One or more victims shot since Columbine: 1,143 school shootings

When a gun is fired on a school campus, all the shots missed roughly half the time (that’s an important story of its own about luck). Kids and teens seem to generally have bad aim and that has policy implications like reducing risk by keeping students from practicing shooting. In 1974, a student on the rifle team at Olean High had good aim and shot 12 people.

Here is a chart with the number of incidents that have at least one victim.

4+ wounded or killed since Columbine: 59 school shootings

A common definition of a “mass shooting” is when there are four or more victims. Taking this approach excludes about 97% of the shootings that happened on campus since Columbine.

Why are four victims a threshold that makes a shooting more important? I don’t think it should be (my article from 2021: Stop the Arbitrary Benchmark for a Mass Shooting). When 20 shots are fired in a crowded hallway, it’s mostly luck if there are 2 victims instead of 20 victims.

4+ killed since Columbine: 8 school shootings

Some definitions of “mass shooting” only include 4 or more victims who are killed. With this threshold, there have been 8 school shootings since Columbine and 14 total since 1966.

Just like the other criteria, living or dying after being shot is also a factor of how lucky you are. Being counted as a fatality versus wounded may be more related to factors like timely EMS care, distance to a trauma center, type of bullet, how many times someone is shot, and location of the gunshot than the intent of the shooter.

If 18 victims were shot but they all got great medical care and lived, does this mean there wasn’t a school shooting? That’s the case if 4+ killed is the threshold.

279 people were shot during these 14 shootings with 4+ fatalities between 1988 and 2023 (four were before Columbine). The shooter(s) died during 9 of the 14 attacks (64%).

Active Shooter since Columbine: 133 school shootings

I personally hate the term “active shooter” but it’s one that we are stuck with because it has become so commonly used. There is no legal or consistently used definition of it.

For my data collection, active shooter is when the shooter killed and/or wounded victims, either targeted or random, within the school campus during a continuous episode of violence.

A map shows active shooter attacks distributed across the country.

Chart of active shooter incidents shows the number per year is increasing over time.

Pre-Planned Attacks since Columbine: 97 school shootings

A different way to think about school shootings is based on the intent rather than the outcomes. I’ve found 97 cases since Columbine where the shooter had some combination of a plan, hitlist, extra ammo, multiple weapons, or made prior threats which all show intent to cause harm.

Near misses since Columbine: 272 school shootings

Based on these real-world incidents, I’ve adapted the aviation definition of near miss to include shootings at schools that had the potential to be much worse (read my article about near misses). A near miss can be an incident without injuries or deaths.

How many school shootings since Columbine?

That answer depends on how you sort the data:

• Any shooting on school property since Columbine: 2,032 school shootings

• One or more victims shot since Columbine: 1,143 school shootings

• 4+ wounded or killed since Columbine: 59 school shootings

• 4+ killed since Columbine: 8 school shootings

• Active Shooter since Columbine: 133 school shootings

• Pre-Planned Attacks since Columbine: 97 school shootings

• Near misses since Columbine: 272 school shootings

When someone is advocating for a specific social agenda, policy, procedure, or security product, the number of school shootings since Columbine can range from 8 to more than 2,000. You can explore the data make your own story with my new Tableau dashboards.

At almost every lecture or training session I’ve attended, someone says “Columbine changed everything” with school security. Based on my research, Columbine inspired at least 23 other school shooters. What more physical security and classroom lockdowns haven’t done over the last 25 years is prevent these attacks.

No matter how you slice up the school shooting data, the trend line is going up and the problem is getting worse. If Columbine did change everything at schools, it changed them for the worse.

---

David Riedman is the creator of the K-12 School Shooting Database and an internationally recognized expert. Listen to my recent interviews on Freakonomics Radio, New England Journal of Medicine, and Iowa Public Radio after the Perry High shooting.