The Data on Mass Shootings

By 

Best in Moderation

Mass shootings are back in the news, but they never really went anywhere. In fact, last year saw a major uptick in mass shootings, clocking in at 611 total incidents. 47 of those had 3 or more deaths.

There is a lot of data around mass shootings, but often enough discussions of them do not include the relevant data, instead banking on emotion, argument over cherry picked races, genders, types of guns, etc. I hope this serves as a bit of a primer for what I am sad to say will probably be many conversations about articles in the future.

To start off with, I’d like to define parameters. I’m going to only use data from several sources when I do comparisons and analysis. That doesn’t mean there isn’t an argument to be made for other comparisons; in fact, if you want to provide it, that can only be helpful for future discussions. Next, sources vary, so I will do my best to use only sources with direct possibilities to check, such as ones who link articles, databases, etc, or are the direct articles and databases themselves. Lastly, I will spend some time at the end debunking myths; I imagine this will be the source for a lot of debate below, but I’m going to make you wade through all the data first 

Sources being used:
https://www.gunviolencearchive.org/past-tolls
https://github.com/StanfordGeospatialCenter/MSA
https://www.motherjones.com/politics/2012/12/mass-shootings-mother-jones-full-data/
https://massshootingtracker.org/data/
https://worldpopulationreview.com/state-rankings/strictest-gun-laws-by-state

Mass Shootings General Data:

Mass shootings in 2019: 417
Total Dead: 465
Incidents with 3 or more dead: 54

Mass shootings in 2020: 611
Total Dead: 513
Incidents with 3 or more dead: 47

Mass Shooting State Details:

2019:

State	Rank (Total Incidents)	Rank (Fatalities)	Incidents	Fatalities	Injuries	Fatality / Incident	Injury / Incident	Population	% Population	% Mass Shootings	Gun Homicides	Gun Homicide Rate / 1M
California	1	2	49	65	49	1.33	1.00	39,512,223	12.04%	11.75%	159	4.02
Illinois	2	3	41	28	182	0.68	4.44	12,671,821	3.86%	9.83%	104	8.21
Texas	3	1	30	73	142	2.43	4.73	28,995,881	8.83%	7.19%	225	7.76
Louisiana	4	5	26	20	106	0.77	4.08	4,648,794	1.42%	6.24%	90	19.36
Maryland	5	13	21	12	85	0.57	4.05	6,045,680	1.84%	5.04%	68	11.25
Georgia	6	10	19	16	74	0.84	3.89	10,617,423	3.23%	4.56%	92	8.67
Pennsylvania	7	11	19	13	84	0.68	4.42	12,801,989	3.90%	4.56%	83	6.48
Missouri	8	6	18	20	60	1.11	3.33	6,137,428	1.87%	4.32%	77	12.55
Florida	9	7	15	20	54	1.33	3.60	21,477,737	6.54%	3.60%	169	7.87
Ohio	10	8	14	20	61	1.43	4.36	11,689,100	3.56%	3.36%	101	8.64
Alabama	11	9	12	17	47	1.42	3.92	4,903,185	1.49%	2.88%	81	16.52
New Jersey	12	14	11	12	47	1.09	4.27	8,882,190	2.71%	2.64%	32	3.60
North Carolina	13	12	11	13	40	1.18	3.64	10,488,084	3.20%	2.64%	77	7.34
Indiana	14	23	10	6	49	0.60	4.90	6,732,219	2.05%	2.40%	47	6.98
South Carolina	15	15	10	10	42	1.00	4.20	5,148,714	1.57%	2.40%	78	15.15
Virginia	16	4	10	21	41	2.10	4.10	8,535,519	2.60%	2.40%	49	5.74
Michigan	17	16	9	8	35	0.89	3.89	9,986,857	3.04%	2.16%	56	5.61
New York	18	20	9	7	43	0.78	4.78	19,453,561	5.93%	2.16%	45	2.31
DC	19	29	7	4	28	0.57	4.00	705,749	0.22%	1.68%	20	28.34
Tennessee	20	30	7	3	32	0.43	4.57	6,829,174	2.08%	1.68%	84	12.30
Arizona	21	21	6	7	26	1.17	4.33	7,278,717	2.22%	1.44%	41	5.63
Mississippi	22	17	6	8	21	1.33	3.50	2,976,149	0.91%	1.44%	43	14.45
Arkansas	23	31	5	3	20	0.60	4.00	3,017,804	0.92%	1.20%	24	7.95
Kentucky	24	24	5	6	18	1.20	3.60	4,467,673	1.36%	1.20%	30	6.71
Massachusetts	25	22	5	7	17	1.40	3.40	6,892,503	2.10%	1.20%	13	1.89
New Mexico	26	18	5	8	18	1.60	3.60	2,096,829	0.64%	1.20%	28	13.35
Colorado	27	33	4	2	20	0.50	5.00	5,758,736	1.75%	0.96%	25	4.34
Kansas	28	25	4	5	16	1.25	4.00	2,913,314	0.89%	0.96%	25	8.58
Oklahoma	29	26	4	5	12	1.25	3.00	3,956,971	1.21%	0.96%	32	8.09
Washington	30	19	4	8	12	2.00	3.00	7,614,893	2.32%	0.96%	31	4.07
Connecticut	31	35	3	1	12	0.33	4.00	3,565,287	1.09%	0.72%	13	3.65
Iowa	32	32	3	3	11	1.00	3.67	3,155,070	0.96%	0.72%	10	3.17
Nevada	33	36	3	1	12	0.33	4.00	3,080,156	0.94%	0.72%	22	7.14
Wisconsin	34	27	3	5	10	1.67	3.33	5,822,434	1.77%	0.72%	29	4.98
Delaware	35	38	2	0	10	0.00	5.00	973,764	0.30%	0.48%	10	10.27
Minnesota	36	37	2	1	12	0.50	6.00	5,639,632	1.72%	0.48%	15	2.66
Montana	37	28	2	5	4	2.50	2.00	1,068,778	0.33%	0.48%	9	8.42
Nebraska	38	39	1	0	4	0.00	4.00	1,934,408	0.59%	0.24%	9	4.65
Oregon	39	40	1	0	5	0.00	5.00	4,217,737	1.28%	0.24%	11	2.61
Wyoming	40	34	1	2	2	2.00	2.00	578,759	0.18%	0.24%	2	3.46
West Virginia	41	NA	NA	NA	NA	NA	NA	1,792,147	0.55%	NA	13	7.25
Alaska	41	NA	NA	NA	NA	NA	NA	731,545	0.22%	NA	10	13.67
Hawaii	41	NA	NA	NA	NA	NA	NA	1,415,872	0.43%	NA	10	7.06
Utah	41	NA	NA	NA	NA	NA	NA	3,205,958	0.98%	NA	7	2.18
Idaho	41	NA	NA	NA	NA	NA	NA	1,787,065	0.54%	NA	6	3.36
Maine	41	NA	NA	NA	NA	NA	NA	1,344,212	0.41%	NA	4	2.98
New Hampshire	41	NA	NA	NA	NA	NA	NA	1,359,711	0.41%	NA	3	2.21
Rhode Island	41	NA	NA	NA	NA	NA	NA	1,059,361	0.32%	NA	3	2.83
South Dakota	41	NA	NA	NA	NA	NA	NA	884,659	0.27%	NA	3	3.39
Vermont	41	NA	NA	NA	NA	NA	NA	623,989	0.19%	NA	2	3.21
North Dakota	42	NA	NA	NA	NA	NA	NA	762,062	0.23%	NA	0	0.00
TOTAL	999		417	465	1563	1.12	3.75	328239523			2220	6.76

2020:

State	Rank (Total Incidents)	Rank (Fatalities)	Incidents	Fatalities	Injuries	Fatality / Incident	Injury / Incident	Population	% Population	% Mass Shootings	Gun Homicides	Gun Homicide Rate / 1M
Illinois	1	1	69	42	301	0.61	4.36	12,671,821	3.86%	11.29%	105	8.29
California	2	2	39	37	153	0.95	3.92	39,512,223	12.04%	6.38%	209	5.29
New York	3	10	38	20	175	0.53	4.61	19,453,561	5.93%	6.22%	44	2.26
Florida	4	4	34	26	133	0.76	3.91	21,477,737	6.54%	5.56%	125	5.82
Pennsylvania	5	14	34	16	138	0.47	4.06	12,801,989	3.90%	5.56%	87	6.80
Texas	6	3	34	37	124	1.09	3.65	28,995,881	8.83%	5.56%	226	7.79
Louisiana	7	9	27	21	113	0.78	4.19	4,648,794	1.42%	4.42%	84	18.07
Ohio	8	8	25	22	111	0.88	4.44	11,689,100	3.56%	4.09%	85	7.27
Missouri	9	6	22	25	96	1.14	4.36	6,137,428	1.87%	3.60%	82	13.36
South Carolina	10	7	22	24	98	1.09	4.45	5,148,714	1.57%	3.60%	45	8.74
Michigan	11	11	20	19	72	0.95	3.60	9,986,857	3.04%	3.27%	84	8.41
North Carolina	12	5	20	26	80	1.30	4.00	10,488,084	3.20%	3.27%	83	7.91
Maryland	13	16	19	11	78	0.58	4.11	6,045,680	1.84%	3.11%	54	8.93
Tennessee	14	21	19	9	85	0.47	4.47	6,829,174	2.08%	3.11%	90	13.18
Georgia	15	13	17	18	73	1.06	4.29	10,617,423	3.23%	2.78%	98	9.23
Mississippi	16	12	17	19	70	1.12	4.12	2,976,149	0.91%	2.78%	40	13.44
Arkansas	17	19	13	10	48	0.77	3.69	3,017,804	0.92%	2.13%	33	10.94
New Jersey	18	17	12	11	51	0.92	4.25	8,882,190	2.71%	1.96%	24	2.70
Alabama	19	15	11	16	37	1.45	3.36	4,903,185	1.49%	1.80%	56	11.42
Colorado	20	25	11	6	52	0.55	4.73	5,758,736	1.75%	1.80%	20	3.47
Virginia	21	33	11	3	46	0.27	4.18	8,535,519	2.60%	1.80%	54	6.33
Kentucky	22	26	10	6	44	0.60	4.40	4,467,673	1.36%	1.64%	52	11.64
Wisconsin	23	18	10	11	42	1.10	4.20	5,822,434	1.77%	1.64%	31	5.32
DC	24	27	8	5	58	0.63	7.25	705,749	0.22%	1.31%	16	22.67
Massachusetts	25	28	8	5	33	0.63	4.13	6,892,503	2.10%	1.31%	11	1.60
Connecticut	26	23	7	7	27	1.00	3.86	3,565,287	1.09%	1.15%	14	3.93
Indiana	27	22	7	9	23	1.29	3.29	6,732,219	2.05%	1.15%	72	10.69
Minnesota	28	39	6	1	34	0.17	5.67	5,639,632	1.72%	0.98%	22	3.90
Washington	29	36	5	2	25	0.40	5.00	7,614,893	2.32%	0.82%	16	2.10
Arizona	30	31	4	4	16	1.00	4.00	7,278,717	2.22%	0.65%	44	6.05
Iowa	31	29	4	5	16	1.25	4.00	3,155,070	0.96%	0.65%	7	2.22
Nevada	32	24	4	7	12	1.75	3.00	3,080,156	0.94%	0.65%	22	7.14
Alaska	33	30	3	5	8	1.67	2.67	731,545	0.22%	0.49%	5	6.83
Delaware	34	34	3	3	11	1.00	3.67	973,764	0.30%	0.49%	13	13.35
New Mexico	35	40	3	1	12	0.33	4.00	2,096,829	0.64%	0.49%	18	8.58
West Virginia	36	20	3	10	7	3.33	2.33	1,792,147	0.55%	0.49%	28	15.62
Kansas	37	44	2	0	9	0.00	4.50	2,913,314	0.89%	0.33%	17	5.84
Nebraska	38	37	2	2	10	1.00	5.00	1,934,408	0.59%	0.33%	5	2.58
Oklahoma	39	41	2	1	7	0.50	3.50	3,956,971	1.21%	0.33%	16	4.04
Oregon	40	42	2	1	7	0.50	3.50	4,217,737	1.28%	0.33%	20	4.74
Idaho	41	38	1	2	3	2.00	3.00	1,787,065	0.54%	0.16%	7	3.92
Maine	42	35	1	3	1	3.00	1.00	1,344,212	0.41%	0.16%	1	0.74
South Dakota	43	43	1	1	3	1.00	3.00	884,659	0.27%	0.16%	4	4.52
Utah	44	32	1	4	1	4.00	1.00	3,205,958	0.98%	0.16%	11	3.43
Hawaii	45	45	0	0	0	NA	NA	1,415,872	0.43%	NA	2	1.41
Montana	45	45	0	0	0	NA	NA	1,068,778	0.33%	NA	9	8.42
New Hampshire	45	45	0	0	0	NA	NA	1,359,711	0.41%	NA	2	1.47
Rhode Island	45	45	0	0	0	NA	NA	1,059,361	0.32%	NA	4	3.78
Wyoming	45	45	0	0	0	NA	NA	578,759	0.18%	NA	1	1.73
North Dakota	46	46	0	0	0	NA	NA	762,062	0.23%	NA	0	0.00
Vermont	46	46	0	0	0	NA	NA	623,989	0.19%	NA	0	0.00
TOTAL	999		611	513	2543	0.84	4.16	328239523			2198	6.70

Mass Shooting Demographics

Average Age of Mass Shooter: 34
Age Range Mass Shooter: 11 – 66 (5% under 18)
Percent showing clear prior indications of violence: 50.4%
Incidents where weapon was legally obtained: 69.7%
Incidents wherein weapon was limited to handguns: 10%
Most Common Guns: Glock 17, AR-15
Perpetrators by race: White (55.46%), Black (19.65%), Latino (8.4%), Asian (6.72%)
Perpetrators by biological sex: Male (97.5%), Female (2.5%)
Event vs Spree Ratio: 84% / 16%

Mass Shooting Claims:

1. Mass shootings occur in states with the most gun ownership
2. Mass shootings drop with more restrictive gun laws
3. Mass shootings are disproportionately perpetrated by white men
4. Mass shootings correlate to the state gun homicide rate
5. Mass shootings are proportional to the population
6. Mass shootings are often done by those with mental illnesses

1. Mostly, no. Out of the top 5 states for gun ownership, none rank even in the top 15 for mass shooting incidents. Lower gun ownership does show some impacts, with two of the lowest 5 having no mass shootings. However, New York, ranked 3 in mass shootings, has the 3rd lowest ownership of guns, thus becoming an outlier for this. Possible explanations can be that gun ownership reporting is lax, and that 30% of guns used in incidents are obtained illegally, but more study would have to be done to see if this explains the outlier in New York. Either way, the claim that lower gun ownership = lower incidents has some support, but higher gun ownership = higher incidents does not.
   
   
2. Again, the data here is a mixed bag. California, rated most restrictive, has the 2nd highest mass shooting incident rate. New Hampshire, with the 2nd most restrictive laws, has the least mass shooting incident rate. The rest of the top 5 range around. Conversely, there doesn’t seem to be any pattern at all to lowered gun restrictions impacting mass shooting incidents; the range is similar, albeit not so obvious as with CA and NH. This claim too seems to be a myth.
   
   
3. As far as biological sex goes, yes, mass shooters are overwhelmingly likely to be men. As far as race goes, there are more perpetrators who are white or black, and less that are latino and Asian, than would be expected based on demographics. The difference isn’t much though, so claiming that being white is a good indicator is not very true. Male = yes, white = no.
   
   
4. Both Louisiana and Missouri fall into the top 5 in gun homicides and top 10 in mass shootings. Conversely, all the lowest gun homicide states appear on the bottom of the incident list. So while it is not a 1:1 relationship, this is somewhat correlated. Interestingly though, the top 5 mass shooting rate states fall pretty much average in other gun homicides. I’d say this is mostly a myth on the extremes, but shows some statistical tendency (which is to be expected, since mass shootings are a part of total homicide statistics).
   
   
5. The top 7 populated states directly link to the top 7 mass shooting incident states, with one exception. Louisiana has only 1.42% of the population but 4.42% of the mass shootings. Interestingly, when you look at the RATE of shootings, a different picture emerges. While CA has 12% of the population, it only has 6.4% of the mass shootings, so it’s share is far below what it should be. This holds true for Texas as well, and to a lesser extent Arizona and Washington. On the flip side, Illinois has 3.86% of the population but 11.29% of all mass shootings, similar to Louisiana and South Carolina, and to a lesser extent Mississippi, Missouri and Pennsylvania. So while nominally the claim is true, as a rate it certainly is not, with several states showing exception.
   
   
6. Not really. Less than 30% of perpetrators of mass shootings had any indications of mental illness, and fewer still were diagnosed (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4318286/). Mostly it’s triggering events that put stress on them, activating their fears. This is why misinformation and conspiracy theories are so dangerous; they tend to be the basis for mass shooting actions.

Summary:

There is a lot to go over when we discuss gun violence in general. Too much to cover in one OP. So I hope this limited data dump of mass shooting information helps to keep the conversations factual and meaningful.

Please ask questions and pose other claims you’d like to see discussed below.