The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about 1,500 km (930 mi) west from Lisbon and about 3,900 km (2,400 mi) east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the Azores, one of the two autonomous regions of Portugal. Its main industries are: agriculture, dairy farming (for cheese and butter products primarily), minor livestock ranching, fishing and tourism, which is becoming the major service activity in the region; added to which, the government of the Azores employs a large percentage of the population directly or indirectly in many aspects of the service and tertiary sectors. There are nine major Azorean islands and an islet cluster, in three main groups. These are Flores and Corvo, to the west; Graciosa, Terceira, São Jorge, Pico and Faial in the centre; and São Miguel, Santa Maria and the Formigas Reef to the east. They extend for more than 600 km (370 mi) and lie in a northwest-southeast direction. The vast extent of the islands defines an immense exclusive economic zone of 1,100,000 km2 (420,000 sq mi). The westernmost point of this area is 3,380 km (2,100 mi) from the North American continent. All the islands have volcanic origins, although some, such as Santa Maria, have had no recorded activity since the islands were settled. Mount Pico, on the island of Pico, is the highest point in Portugal, at 2,351 m (7,713 ft). The Azores are actually some of the tallest mountains on the planet, measured from their base at the bottom of the ocean to their peaks, which thrust high above the surface of the Atlantic. Because these once-uninhabited and remote islands were settled sporadically over a span of two centuries, their culture, dialect, cuisine and traditions vary considerably.