Mass shootings are increasing in Colorado. Here are three charts that explain the trend.

By one measure, the shooting at Club Q in Colorado Springs late Saturday and early Sunday was the worst the state has seen in more than a decade.

The at least 22 victims — 5 killed and 17 injured by gunfire — are the most in a Colorado shooting since the July 2012 attack on a movie theater in Aurora.

Since 2013, there have been 61 shootings in the state in which four or more people, excluding the perpetrator, were shot.

A total of 328 people were shot in those attacks, including 82 who were killed and 246 who were wounded.

Mass shootings are increasing in Colorado

The attack at Club Q fits into a trend: Mass shootings are increasing in Colorado. This year will finish as the worst year for mass shootings in the last decade, with at least 13. Of the 61 mass shootings since 2013, more than half — 36 — have occurred in the last three years.

Most mass shootings occur in Colorado’s largest cities

Since 2013, mass shootings have occurred in 15 cities and towns in Colorado. All but two of those are on the Front Range, but the list shows that mass shootings are not just an urban problem. One of the shootings, in which three people were killed and one was injured, occurred in the southern San Luis Valley community of Capulin.

The majority of mass shootings over the last decade in Colorado have occurred in the state’s three largest cities — Denver, Colorado Springs and Aurora. Together, they combine for 47 of the 61 mass shootings. Denver has the most with 24, while Aurora has seen 12 mass shootings and Colorado Springs has seen 11.

In terms of the most deadly mass shootings — those in which at least four people were shot and three or more people were killed — there have been eight in Colorado since 2013. Three of those occurred in Colorado Springs, two in Denver and one each in Aurora, Boulder and Capulin.

Defining a “mass shooting”

Tracking data on mass shootings is difficult, in part because “mass shootings” as a category of violence is so broad that it contains myriad genres and subgenres.

Some lists, like one maintained by Mother Jones magazine, track only mass shootings that are seemingly indiscriminate and occur in public settings. That covers shootings such as the one at Club Q or the Aurora theater. But it leaves out other forms of mass violence, such as a shooting at a house in Aurora in October that killed four people.

Other lists define mass shootings mathematically — such as the shooting tracker maintained by the Gun Violence Archive, which catalogs shootings in which at least four people are shot, not including the gunman. These lists collect data on more shootings, including many that don’t receive a lot of media attention. But they also exclude shootings that fit within a genre of American mass violence: attacks intended to sow terror in public spaces. For instance, the attack on a Thornton Walmart store in 2017 that killed three people is not in the Gun Violence Archive’s database.

The Federal Bureau of Investigation defines a mass shooting more strictly than most — an event in which four or more people are shot to death. Alternately, the FBI produces an annual report on “active shooter incidents,” a genre of violence defined by the actions of the perpetrator and not by the number of people wounded or killed.

Compounding the problem is that there is no consensus method for aggregating data on shootings, meaning most lists of mass shootings rely on media reports and can, at times, have errors in the numbers.To create these charts, The Colorado Sun used data from the Gun Violence Archive. The organization began tracking shootings in 2013, the year after the shootings at the Aurora movie theater and at Sandy Hook Elementary School in Newtown, Connecticut.

So it is not a compendium of information on mass shootings in Colorado — notably it excludes the shooting at Columbine High School in 1999, among many others. But it is the most complete data source available over the last decade.

Update: This story was updated at 1:17 p.m. on Monday, Nov. 21, 2022, after Colorado Springs police released updated information on the shooting at Club Q. Police now say that 17 people were wounded by gunfire in the shooting, while another person was injured but wasn’t shot during the attack. The charts have also been updated to reflect this new information.