The Data on Mass Shootings

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:

StateRank (Total Incident)Rank (Fatalities)IncidentsFatalitiesInjuriesFatality / IncidentInjury / IncidentPopulation% Population% Mass ShootingsGun HomicidesGun Homicide Rate / 1M
California124965491.331.0039,512,22312.04%11.75%1594.02
Illinois2341281820.684.4412,671,8213.86%9.83%1048.21
Texas3130731422.434.7328,995,8818.83%7.19%2257.76
Louisiana4526201060.774.084,648,7941.42%6.24%9019.36
Maryland5132112850.574.056,045,6801.84%5.04%6811.25
Georgia6101916740.843.8910,617,4233.23%4.56%928.67
Pennsylvania7111913840.684.4212,801,9893.90%4.56%836.48
Missouri861820601.113.336,137,4281.87%4.32%7712.55
Florida971520541.333.6021,477,7376.54%3.60%1697.87
Ohio1081420611.434.3611,689,1003.56%3.36%1018.64
Alabama1191217471.423.924,903,1851.49%2.88%8116.52
New Jersey12141112471.094.278,882,1902.71%2.64%323.60
North Carolina13121113401.183.6410,488,0843.20%2.64%777.34
Indiana1423106490.604.906,732,2192.05%2.40%476.98
South Carolina15151010421.004.205,148,7141.57%2.40%7815.15
Virginia1641021412.104.108,535,5192.60%2.40%495.74
Michigan171698350.893.899,986,8573.04%2.16%565.61
New York182097430.784.7819,453,5615.93%2.16%452.31
DC192974280.574.00705,7490.22%1.68%2028.34
Tennessee203073320.434.576,829,1742.08%1.68%8412.30
Arizona212167261.174.337,278,7172.22%1.44%415.63
Mississippi221768211.333.502,976,1490.91%1.44%4314.45
Arkansas233153200.604.003,017,8040.92%1.20%247.95
Kentucky242456181.203.604,467,6731.36%1.20%306.71
Massachusetts252257171.403.406,892,5032.10%1.20%131.89
New Mexico261858181.603.602,096,8290.64%1.20%2813.35
Colorado273342200.505.005,758,7361.75%0.96%254.34
Kansas282545161.254.002,913,3140.89%0.96%258.58
Oklahoma292645121.253.003,956,9711.21%0.96%328.09
Washington301948122.003.007,614,8932.32%0.96%314.07
Connecticut313531120.334.003,565,2871.09%0.72%133.65
Iowa323233111.003.673,155,0700.96%0.72%103.17
Nevada333631120.334.003,080,1560.94%0.72%227.14
Wisconsin342735101.673.335,822,4341.77%0.72%294.98
Delaware353820100.005.00973,7640.30%0.48%1010.27
Minnesota363721120.506.005,639,6321.72%0.48%152.66
Montana37282542.502.001,068,7780.33%0.48%98.42
Nebraska38391040.004.001,934,4080.59%0.24%94.65
Oregon39401050.005.004,217,7371.28%0.24%112.61
Wyoming40341222.002.00578,7590.18%0.24%23.46
West Virginia41NANANANANANA1,792,1470.55%NA137.25
Alaska41NANANANANANA731,5450.22%NA1013.67
Hawaii41NANANANANANA1,415,8720.43%NA107.06
Utah41NANANANANANA3,205,9580.98%NA72.18
Idaho41NANANANANANA1,787,0650.54%NA63.36
Maine41NANANANANANA1,344,2120.41%NA42.98
New Hampshire41NANANANANANA1,359,7110.41%NA32.21
Rhode Island41NANANANANANA1,059,3610.32%NA32.83
South Dakota41NANANANANANA884,6590.27%NA33.39
Vermont41NANANANANANA623,9890.19%NA23.21
North Dakota42NANANANANANA762,0620.23%NA00.00
TOTAL99941746515631.123.7532823952322206.76

2020:

StateRank (Total Incident)Rank (Fatalities)IncidentsFatalitiesInjuriesFatality / IncidentInjury / IncidentPopulation% Population% Mass ShootingsGun HomicidesGun Homicide Rate / 1M
Illinois1169423010.614.3612,671,8213.86%11.29%1058.29
California2239371530.953.9239,512,22312.04%6.38%2095.29
New York31038201750.534.6119,453,5615.93%6.22%442.26
Florida4434261330.763.9121,477,7376.54%5.56%1255.82
Pennsylvania51434161380.474.0612,801,9893.90%5.56%876.80
Texas6334371241.093.6528,995,8818.83%5.56%2267.79
Louisiana7927211130.784.194,648,7941.42%4.42%8418.07
Ohio8825221110.884.4411,689,1003.56%4.09%857.27
Missouri962225961.144.366,137,4281.87%3.60%8213.36
South Carolina1072224981.094.455,148,7141.57%3.60%458.74
Michigan11112019720.953.609,986,8573.04%3.27%848.41
North Carolina1252026801.304.0010,488,0843.20%3.27%837.91
Maryland13161911780.584.116,045,6801.84%3.11%548.93
Tennessee1421199850.474.476,829,1742.08%3.11%9013.18
Georgia15131718731.064.2910,617,4233.23%2.78%989.23
Mississippi16121719701.124.122,976,1490.91%2.78%4013.44
Arkansas17191310480.773.693,017,8040.92%2.13%3310.94
New Jersey18171211510.924.258,882,1902.71%1.96%242.70
Alabama19151116371.453.364,903,1851.49%1.80%5611.42
Colorado2025116520.554.735,758,7361.75%1.80%203.47
Virginia2133113460.274.188,535,5192.60%1.80%546.33
Kentucky2226106440.604.404,467,6731.36%1.64%5211.64
Wisconsin23181011421.104.205,822,4341.77%1.64%315.32
DC242785580.637.25705,7490.22%1.31%1622.67
Massachusetts252885330.634.136,892,5032.10%1.31%111.60
Connecticut262377271.003.863,565,2871.09%1.15%143.93
Indiana272279231.293.296,732,2192.05%1.15%7210.69
Minnesota283961340.175.675,639,6321.72%0.98%223.90
Washington293652250.405.007,614,8932.32%0.82%162.10
Arizona303144161.004.007,278,7172.22%0.65%446.05
Iowa312945161.254.003,155,0700.96%0.65%72.22
Nevada322447121.753.003,080,1560.94%0.65%227.14
Alaska33303581.672.67731,5450.22%0.49%56.83
Delaware343433111.003.67973,7640.30%0.49%1313.35
New Mexico354031120.334.002,096,8290.64%0.49%188.58
West Virginia362031073.332.331,792,1470.55%0.49%2815.62
Kansas37442090.004.502,913,3140.89%0.33%175.84
Nebraska383722101.005.001,934,4080.59%0.33%52.58
Oklahoma39412170.503.503,956,9711.21%0.33%164.04
Oregon40422170.503.504,217,7371.28%0.33%204.74
Idaho41381232.003.001,787,0650.54%0.16%73.92
Maine42351313.001.001,344,2120.41%0.16%10.74
South Dakota43431131.003.00884,6590.27%0.16%44.52
Utah44321414.001.003,205,9580.98%0.16%113.43
Hawaii4545000NANA1,415,8720.43%NA21.41
Montana4545000NANA1,068,7780.33%NA98.42
New Hampshire4545000NANA1,359,7110.41%NA21.47
Rhode Island4545000NANA1,059,3610.32%NA43.78
Wyoming4545000NANA578,7590.18%NA11.73
North Dakota4646000NANA762,0620.23%NA00.00
Vermont4646000NANA623,9890.19%NA00.00
TOTAL99961151325430.844.1632823952321986.70

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 way 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.

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