Four victims, at least ... to count as a "mass" shooting.
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On that basis, 632 might become as much 684 by the end of December, if the weekly average is consistent. There were 39 incidents in the first 24 days of 2023.

hmmm, the jump in 2019 - 2020 *might* be related to the stresses caused by covid regulations during the global pandemic, some affects of which are still present.
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not my image : fair use & public education