No larger point to be made here, but Mother Jones' dataset of mass shootings is way above any other source I've come across in my research. For starters, they have a very solid definition of mass shootings that isn't hyper politicized like those used by advocacy groups such as Every Town. The data is also pretty dense, and helpful.
One trend to noodle on is the sudden drop in mass shootings in 2020. There were only two.
weird, this kinda resembles population density, except that giant blip where the VA tech shooting happened, the Orlando night club, columbine CO, and that giant blip in Vegas where the dude with a bump stock took out 58 people.
also, schools and most businesses were closed in 2020, so there is that.