São Jorge (Portuguese pronunciation: [sɐ̃w ˈʒɔɾʒɨ]) is an island in the central group of the Azores archipelago and part of the autonomous region of Portugal. Separated from its nearest neighbours (Pico and Faial islands) by the 15-kilometre (9.3 mi) Pico-São Jorge Channel, the central group is often referred colloquially as part of the Triângulo ("Triangle") group or just "The Triangle". São Jorge is a relatively long thin island with tall cliffs, whose 8,381 inhabitants are concentrated on various geological debris fields (fajãs) along the north and south coasts; from east to west, the island is 53 kilometres (33 mi) long and, north to south, 8 kilometres (5.0 mi) wide: its area is 237.59 square kilometres (91.73 sq mi).
Unique among the islands of Azores, São Jorge is uncharacteristically long and slender and susceptible to ocean erosion. The island was built on fissural volcanism associated with the plate tectonics of the mid-Atlantic Ridge and a transform fault that extends from the Ridge to the island of São Miguel (referred to as the São Jorge Fault). Through successive fissural eruptions the island was built up: the only remnants of these forces are the line of volcanic cones that extend along the central ridge (approximately 700 metres in altitude).
It is unclear when the first explorers discovered the island of São Jorge; as part of the politics of human occupation, the Azores were populated after 1430 (probably 1439) through the initiative of Prince Henry the Navigator. 23 April, known as the feast day of Saint George, has been cited by historians as the reason for the island's name, although this is likely conjecture. Genovese and Catalan maps of the 14th century originally designated the long, slender island "São Jorge", a designation that was maintained by Infante D. Henrique when settlers from northern Europe began to colonize the island (around 1460, or twenty years after it was first sighted).
Periods of local prosperity or misery occurred in the following years; there were several bad growing seasons and natural catastrophes (such as the earthquakes, volcanic eruptions and tornados in 1580, 1757, 1808 and 1899) that created famines and hardships. The most famous of these eruptions began in the early morning of May 1, 1808 (Urzelina eruption). Suffocating gases, as well as carboxylic acid, were emitted from a vent along the Manadas ridge and thick greenish vaporous clouds (of chloric and sulfuric acids) rapidly spread to the plants. Eight major tremors were recorded per hour that caused widespread panic. Many of the homes, buildings and cultivatable lands were destroyed. Between 1580 and 1907, at least six significant eruptions occurred; ten people were killed during the 1580 eruption and eight in 1808. In 1850, the island's vineyards were devastated by the phylloxera plague, which had a terrible effect on the economy until the development of the orange industry (about 1860). The island's isolation ended after the completion of the ports of Velas and Calheta.
The last terrestrial volcanic eruption on the island of São Jorge was the eruption of “Vulcão da Urzelina” in 1808.
After a period of small subsistence agriculture, the local economy began to concentrate on a few chief exports: initially, lichen (Roccella tinctoria) and woad (Isatis tinctoria), later the introduction of wheat and corn crops. Woad was one of the most important exports from São Jorge and the Azores; it was initially introduced by Willem van der Hagen around 1490, and exported primarily to his countrymen in Flanders. Both woad and lichen were very popular in central Europe as a dye.
Long before whale-watching became important, whaling was an important industry between the end of the 19th century and middle of the 20th century, where a majority of the inhabitants were tied exclusively to this economy. In strategic locations along the coast, small huts were built to watch-out for whales and give an alarm to the local hunters, who would sail out and harpoon the mammals. Later, when this hunt was prohibited, the islanders began to "hunt" Albacor and Bonito Tuna resulting in the creation of two processing plants in Calheta. Fishing continues to be an important part of the local economy, although whale-watching has turned into a part of local tourism.
While cereals, vineyards and local vegetables are still grown sporadically around the island (much like the other islands of the Azores) the economy of São Jorge is currently dependent on the dairy industry. The local São Jorge cheese has been the most important part of the local economy, resulting in the establishment of an order, the Confraria do Queijo de São Jorge, to promote the consumption and sale of this popular cheese. In addition, Uniqueijo União de Cooperativeas Agrícolas de Lacticínios de São Jorge (Cooperative Agricultural Union of São Jorge Dairy Producers) is the principal dairy-producer on the island. A union of eight cooperatives, Uniqueijo is dedicated to the commercialization of the traditional São Jorge cheese, including new products classified under the DOP Denominação de Origem Protegida (Denomination of Protected Origin) status.