The North Slope is known for having lots of oil. The "National Petroleum Reserve–Alaska" and the "Prudhoe Bay Oil Field" are the two biggest areas where oil is found. The Arctic National Wildlife Refuge is there also, and there has been a lot of debate about drilling for oil there. The oil from the North Slope is pumped south in pipes, called the Trans-Alaska Pipeline System, to Valdez where it is loaded onto ships.