In Coal in Our Veins, Erin Thomas employs historical research, autobiography, and journalism to intertwine the history of coal, her ancestors' lives mining coal, and the societal and environmental impacts of the United States' dependency on coal as an energy source. In the first part of her book, she visits Wales, native ground of British coal mining and of her emigrant ancestors. The Thomases' move to the coal region of Utah—where they witnessed the Winter Quarters and Castle Gate mine explosions, two of the worst mining disasters in American history—and the history of coal development in Utah form the second part.

Then Thomas investigates coal mining and communities in West Virginia, near her East Coast home, looking at the Sago Mine collapse and more widespread impacts of mining, including population displacement, mountain top removal, coal dust dispersal, and stream pollution, flooding, and decimation. The book's final part moves from Washington D.C.—and an examination of coal, CO2, and national energy policy—back to Utah, for a tour of a coal mine, and a consideration of the Crandall Canyon mine cave-in, back to Wales and the closing of the oldest operating deep mine in the world and then to a look at energy alternatives, especially wind power, in West Virginia and Pennsylvania.