The US coal industry is falling apart. Here’s the surprising reason why.

Consider this remarkable fact, from a new report by the Rhodium Group:

The four largest US miners by output (Peabody Energy, Arch Coal, Cloud Peak Energy, and Alpha Natural Resources), which account for nearly half of US production, were worth a combined $34 billion at their peak in 2011. Today they are worth $150 million.

Dozens of US mining companies have declared bankruptcy in the past few years. More are on the verge.

What’s going on? What is killing US coal?

The conventional answer to that question is that less coal is being burned for electricity in the US, thanks to cheap natural gas, renewables, and federal regulations.

And that’s part of it. But not the only part, or even the biggest. The biggest driver of US coal’s decline isn’t happening in the US at all.

To see what it is, let’s look at the latest company to go under.

[“Source-vox”]