Factors that come to mind:

1) population density
2) over-connectedness (24 hour 'news cycle', social media, electronic media/cable TV)

That may play a small part, but the systematic and willful breakdown of gender/parental roles and family values is closer to the heart of the matter.

A few quick questions:
How are you defining what is a school shooting?

Where are you getting records and can they be verified (especially the stuff from the 19th century)?

Here's the chart as a percentage of the population. You can see the wheels started to come off in 1980.

I simply took the Wikipedia article posted on the other thread and popped it into a spreadsheet. I obviously have not nor do I plan to scrub that data. So absorb this information like anything else you would on the web; with caution.

https://en.wikipedia.org/wiki/List_of_school_shootings_in_the_United_States

Very poor stats.

"A criminal justice club student picked up a loaded gun, belonging to an advisor, which the student thought was an unloaded training weapon. She then shot at a wall target, unintentionally firing a bullet, which went through the wall and broke a window. The advisor was a licensed peace officer permitted to carry a firearm on campus"

That isn't a school shooting.

"Central Michigan University shooting: 19-year-old student James Eric Davis Jr. shot and killed his mother and father when they came to campus to take him home for spring break. After the shooting Davis fled and the campus was placed on lockdown. Around 15 hours later police arrested him and took him to a local hospital. The incident disrupted the travel plans of students and campus activities for several days. Davis was charged with two counts of murder and one count of unlawful possession of a firearm used to commit murder."

Not a school shooting.

"A police officer was shot outside a school in a school zone while he was directing school buses into J.B. Martin Middle School, and the suspect was apprehended at the scene"

Not a school shooting.

"A teenager was found killed in the parking lot of Tenaya Middle School. The shooting was reported to have occurred after school hours"

Not a school shooting.

Do you have better stats? So take that data point out... In fact take out 10% of them. Heck take out 50% of them. The story is still black and white. OR, are you arguing school shootings are actually not more common now than they were in decades past?

My goal here was to start a discussion about what's changed here since the 1980's. Something has.

The list would be better described as "death resulting from violence on school grounds" Not all of them are traditional mass shootings. That's true up and down the data set. On the net net, it paints a real story. School shootings have gone up dramatically overtime. Present data to the contrary, or lets get back to a meaningful conversation.

No the list would be better titled "gun control propaganda".

The first one I listed nobody was even injured. It was an accident in a criminal justice class.