The Trans-Alaska pipeline is the main trunk of the Trans-Alaska Pipeline System, one of the largest in the world. Built after the oil price spike of the 1970s made production in Alaska’s icy North Slope economically feasible, the pipeline now transports so little oil that pumping stations are being closed in order to adjust to declining flow rates. The reason for this is simple: shale. The US shale boom is producing more oil cheaper and easier in the lower 48, making more difficult and expensive production zones like Alaska’s Prudhoe Bay and the Gulf of Mexico much less attractive to producers.