DENVER (AP) — Authorities investigating the cause of a wildfire that destroyed more than 1,000 buildings last month in Colorado are looking at the possibility that the blaze is linked to underground coal fires have long smoldered at old coal mines in the area.

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Authorities say the mines are just one of the possible causes they are looking into.

Across the U.S. officials are tracking more than 200 underground mine fires in more than a dozen states, and those are just the ones documented.

As climate change leads to drought across large swaths of a U.S. West that's already seeing longer and more destructive fire seasons, experts say smoldering coal fires will pose a continuing threat.

LOOK: Dramatic Photos Show Fires Near Wyoming Border

The Richard Spring and Lame Deer fires near the Wyoming border threatened several communities in southern Montana. Currently, firefighters are nearing complete containment on the blazes.