During the first years of Pennsylvania’s oil boom, crude oil covered almost everything. Oil soaked the ground, pooled in pits, and ran through creeks before anyone fully understood the consequences. Travelers who visited the Oil Region in the 1860s often left with the same impression: the smell of petroleum hung in the air. It clung to clothes, tools, buildings, and sometimes, even the animals that lived alongside the oil fields. One visitor famously wrote that in th