At some point today, you will probably flip on a light switch. That simple action connects you to the oldest and most plentiful source of American electricity: coal.

Since the early 1880s — when Edison and Tesla pioneered the distribution of electrical power into our homes — most of that power has come from the process of burning coal.

Four years ago, something started to change. First it was slow, and then this past month that change became dramatic. Coal now generates just 34 percent of our electricity, down from about 50 percent just four years ago.

Now, the loss of coal as the dominant energy source is having damaging effects on the towns that once relied on the black rock for their livelihood.