Is Las Vegas the worst mass shooting in US history? It’s surprisingly complicated.

It’s already been said again and again in the span of a day: The shooting at the Route 91 Harvest Festival in Las Vegas, with at least 58 dead and hundreds injured, was the deadliest mass shooting in American history.

But was it really? The answer, it turns out, is surprisingly complicated.

The short version: It was definitely the deadliest mass shooting in recent history. But if you look further back in the US’s past, the real answer depends on how you define a mass shooting.

The National Association of Black Journalists and the National Association of Hispanic Journalists, for example, pointed to two past attacks as examples of previous massacres with higher death tolls than the Las Vegas shooting.