I was intrigued by the different narratives going around about “who” the majority of mass shooters in the US are. Essentially there are two camps; the “most mass shooters are middle aged white men” camp, and the “no they’re not”, for lack of a better name, camp. The main source for this is an analytic three part series by Benjamin Radford of the Center for Inquiry, an online journal that “strives to foster a secular society based on reason, science, freedom of inquiry, and humanist values.” Radford also includes links to other data sources within the body of the article. Below is my interpretation and analysis* of the info, and source info links (many of which can be found in Radford’s article as well).
The table below is sourced from an original research study by Emma Fridel and includes a lot of unvarnished and non-contextualized data. But in the chart (and the portions of the article by Radford), there is general takeaway, which are that mass shooting data varies based on the type of shooting event. There are three categories; “Family” (family annihilators), “Felony” (this is usually referencing drive-by and gang or drug related type shootings), and “Public” (which is what people generally think of when they think of a “mass shooting.) The other takeaway, noted in the body of the article, seems to suggest that, for those arguing whether or not mass shooting is a “white male” problem, that this largely depends on the definition one is using for “mass shooting”. If Felony or Family mass killings are included in the data, white men are not overly represented. However, if we are only discussing PUBLIC mass shootings, then, yes, non-hispanic white men technically are the majority of mass shooters.)
Typically, although Family and Felony killings fit the technical description of mass killings that I learned in my criminology courses (3 or more fatalities in a single event/episode of killing), they are not in fact what most people think of when the words “mass shooting” are used.
The New York Times noted (also quoted in the above referenced article, and worth mentioning,) noted that “As convenient as it would be, there is no one-size-fits-all profile of who carries out mass shootings in the United States. About the only thing almost all of them have in common is that they are men. But those men come from varying backgrounds, with different mental health diagnoses and criminal histories.”
And of course the media plays a big role in which events garner coverage, and the narrative that plays out around the events.(IV) (VII) And “the media” is of course, not one big conspiratorial entity. Which version of events you are served depends on the source, and all bets for “truth in reporting” are off since the revocation of the FCC Fairness Doctrine. (VI) We are told mass shootings are not as common as we are lead to believe, and whether or not a given shooting garners attention often has to do with the “pitiability” and perceived “innocence” of the victims. Victims of a gang-related mass killings, for example, are generally viewed as less deserving of sympathy and less “marketable” by some news outlets (even if they are innocent victims caught in cross-fire), than, say, a bunch of hapless church or movie goers, or children in a school.
So to sum up, the who of mass shootings may depend on the definition one is using of “mass shooting”, and what’s more, the usefulness of any analysis of what leads a person to become a mass killer or the “causes” of mass shooting events may be limited unless we can all agree on context.

(SOURCE) (I)
I) Fridel, Emma E. 2017. A multivariate comparison of family, felony, and public mass murders in the United States. Journal of Interpersonal Violence (November 1).
II) https://www.politifact.com/punditfact/statements/2017/oct/06/newsweek/are-white-males-responsible-more-mass-shootings-an/
III) https://www.theguardian.com/us-news/2019/aug/04/mass-shootings-white-nationalism-linked-attacks-worldwide
IV)https://centerforinquiry.org/blog/how-common-are-mass-shootings-the-nature-and-frequency-of-mass-shootings/
V) https://www.nytimes.com/interactive/2019/05/11/us/school-shootings-united-states.html
VI) https://en.wikipedia.org/wiki/FCC_fairness_doctrine
VII) https://centerforinquiry.org/blog/why-isnt-the-media-covering-this-story-or-are-they/
*Note: I did my best to offer a brief and unbiased interpretation of data, based on the information I reviewed. I hope you find it useful and that I didn’t botch too badly.
Related articles by ARQ:
https://alienredqueen.wordpress.com/2018/02/20/can-we-fix-whats-broken-here/