From wikipedia:

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

> The United States has had more mass shootings than any other country.

Wikipedia as primary source?

If you'll check the references for that statement, they're all news articles based on a single study.

A study that the link above already discussed. A study that "excluded gang-related shootings, drive-by shootings, hostage-taking incidents, robberies and acts of genocide or terrorism."[1]

In other words, it's a custom-designed, cherry-picked statistic designed to make the US look worse than it is.

1: https://www.washingtonpost.com/politics/2018/09/05/does-us-l...

It's not cherry picked, it focuses on the phenomenon of mass shootings specifically. Gang wars and genocide are certainly tragic, but they are a very different type of gun violence than what people mean by mass shootings. The study is asking why in America people are shot by the tens or hundreds at ordinary, law-abiding venues such as schools or concerts, which is relevant in its own right.

Actually the study defines "mass" as four or more victims, not tens or hundreds.

And I've never understood who decides whether a mass killing is an "act of terrorism" or not.

I'm shocked. The country that leads the world in stereotypically American mass shootings, narrowly defined to fit our cultural context and exclude problems endemic to other countries, according to one study quoted by the Amazon Post and other left-leaning outlets, is the USA. Say it ain't so.