I heard that mold wiped out almost all of the American chestnut trees. They used to be all over Appalachia. You could walk into the woods anywhere and fill a basket with chestnuts in minutes.
The estimates range from 25%-30% of every tree was an American chestnut. They were effectively eradicated when an infected Chinese chestnut was imported that released chestnut blight. Some of the older root systems still send up small trees, though they tend to die before maturity due to the blight. It's fairly rare for one to live long enough to produce chestnuts.