When oil was discovered at Prudhoe Bay on Alaska's North Slope in 1968, the Eskimo villages of the region scattered around the ten-billion-barrel oil field were similar to most other rural native villages in the state: poor and isolated, with high unemployment, little or no prospect for local economic development, and dependent on federal and state programmes for minimum levels of education, medical care, and other services. Soon after the Prudhoe Bay discovery, however, Eskimo leaders on the North Slope began taking steps toward creation of a borough—a form of local or regional government in Alaska somewhat like a county elsewhere in the United States, but potentially having more extensive powers of taxation and regulation, and greater independence from the state government, than county governments typically possess. Incorporated in 1972, the North Slope Borough covers an area of 228 800 km2 and makes up about 15 per cent of the land area of Alaska. Within its boundaries lie the 93 435 km2 National Petroleum Reserve and most of the 35 560 km2 Arctic National Wildlife Range; both of these areas are under the jurisdiction of the federal Department of Interior. Located between these two federal land areas is the Prudhoe Bay oil field complex, which occupies state lands leased to the oil companies. Extending south from the oil field and crossing the borough's southern border is 270 km of the 1 270 km trans-Alaska oil pipeline.