Crackling fires have long been an idyllic gathering place where chestnuts are roasted, stories shared and souls warmed. Some folks cut their own wood and let it season, but most buy their wood without much thought about where it came from. As it happens, where our firewood comes from matters a lot. The U.S. National Parks Service recommends getting firewood within 10 miles of its destination, and never more than 50 miles. Transporting it longer distances — say, from a farm to your home, significantly increases the chances of introducing invasive pests into the local ecosystem. And those pests can inflict devastating damage on local forests. Some bundles of firewood bear a state or federal stamp certifying that they've been heat-treated to kill pests.