What fuels your world? If you were a colonist or a citizen of the early United States, the answer would be firewood—the material that not just warmed people’s bodies, but allowed them to power the expansion of a new nation.

In many ways, firewood helped create America. But it also threatened to destroy it by sparking an ecological crisis that’s still going on today.

People have been burning wood for warmth for millennia, and in Britain, like the rest of the medieval world, a booming timber industry supplied firewood to people rich and poor. In the 1500s, though, the unthinkable happened—Britain began to run out of firewood.

It was a matter of simple deforestation. Once the forests of the island—a mere 93,000 square miles—were depleted, they didn’t grow back quickly enough to sustain its population’s need for heat, especially as urban populations boomed. In addition, other uses for wood, including the production of paper and increased urban building, pushed the timber industry to its limits.

This wood crisis swept through all of Europe, and even Britain’s dense forests weren’t enough to keep up with wood demand. That shortage hit the poor hard. As economic historian John U. Nef notes, “the price of wood in England rose very much faster than that of any other commodity in general use anywhere.” And no fire meant no food or warmth.

As Britain struggled to figure out how to warm itself, poor English people had two options: wait for an answer, or freeze to death. Many decided to take their chances in the colonies instead.

England’s forests struggled, but in America the scene was completely the opposite. Early settlers marveled at the New World’s seemingly unlimited forests. Then, they cut them down.

It wasn’t just a thirst for fuel. Rather, the abundant trees were seen as obstacles that had to be cleared to make way for farms, cities and roads. They were also perceived as scary by the colonists. The very idea of wilderness—uncontrollable and wild—unnerved settlers. In 1662, Michael Wigglesworth, a Puritan clergyman, characterized the “dark and dismal western woods” as “a waste and howling wilderness” only inhabited by savages and evil forces.

Anxious about the abundant forests, early settlers set to work establishing a thriving logging industry. And they largely ignored early efforts to restrain logging, like a 1681 ordinance by William Penn that required settlers to leave one acre of trees for every five acres cleared.

Pilgrims around a campfire with small cauldron as a man with hatchet is gathering firewood. (Credit: Universal History Archive/UIG via Getty images)

“To them, the sight of a wheat field or a cabbage garden would convey pleasure far greater than that of the most romantic woodland views,” wrote Isaac Weld, an Irish man who traveled throughout the United States between 1795 and 1797. “They have an unconquerable aversion to trees, and whenever a settlement is made, they cut away all before them without mercy; not one is spared.”

Ironically, that demand for firewood led to shortages in the New World, too. As early as the 1740s, people like Benjamin Franklin complained about the lack of firewood, and the colonies began to import firewood from other areas. But still the thirst continued, and by 1769 colonists needed an area as large as Massachusetts, Connecticut, New Hampshire and Vermont combined to satisfy their need for firewood.

In an incredibly short period of time, colonists and members of the new republic decimated American forests. Between 1650 and 1850, settlers managed to cut down half of the Northeast’s forest cover and remove most non-forest timber. This only increased as the United States industrialized. According to the U.S. Energy Information Administration, wood use for fuel spiked around 1870, providing 90 percent of railroad fuel. At its peak, the per capital consumption of firewood was a whopping 4.5 cords per capita. (One cord of firewood is four feet high by four feet wide by eight feet long.)

Late in the 19th century, though, coal became the fuel of choice. But by then, it was too late for America’s forests. The composition of their trees changed significantly, and a lack of forest cover led to soil erosion. Animals were driven from their habitats, and the soil was stripped of vital nutrients. This led to flooding and trouble suppressing fires.

The crisis continues. Though the United States now has more trees than it did a century ago, the North American Forest Commission estimates that there are only two-thirds as many trees as there were in 1600.

Would the United States have been the same without the settlers who, fueled by a firewood shortage, emigrated for a warmer future? Probably not. Nor would its economy be the same without the boost provided by early firewood. Eventually, the United States began to protect its forests. But for a modern-day American, it’s just as impossible to imagine an America with its original, virgin forests as it is to envision the country without the legacy of the fuel they provided.