There are fewer than 8,000 people in Cushing.

But what it lacks in population it makes up for in sheer volume of crude oil. All across the small Oklahoma town giant vats of the stuff dwarf the modest houses. The tanks can collectively store nearly 80 million barrels, which amounts to nearly a day’s supply for the entire world.

Cushing is at the centre of an enormous network of pipes that move millions of barrels...