The Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean. The Portuguese archipelago 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 archipelago, and economic exclusion zone, forms 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. In addition, the government of the Azores is responsible for employing a large percentage of population directly or indirectly in many aspects of the service and tertiary sectors.
There are five cities in the Azores: Ponta Delgada and Ribeira Grande on the island of São Miguel; Angra do Heroísmo and Praia da Vitória on the island of Terceira, and Horta on Faial. Three of these Ponta Delgada, Angra and Horta are considered capital/administrative cities to the regional government: homes to the President (Ponta Delgada), the Judiciary (Angra) and the Regional Assembly (Horta). Angra also serves as the ecclesiastical centre of the Roman Catholic Diocese of Angra.
In 1944, American forces constructed a small and short-lived air base on the island of Santa Maria. In 1945, a new base was constructed on the island of Terceira and is currently known as Lajes Field. This base is in an area called Lajes, a broad, flat sea terrace that had been a farm. Lajes Field is a plateau rising out of the sea on the northeast corner of the island. This Air Force base is a joint American and Portuguese venture. Lajes Field continues to support United States and Portuguese military operations. During the Cold War, the United States Navy P-3 Orion anti-submarine squadrons patrolled the North Atlantic for Soviet submarines and surface spy vessels. Since its inception, Lajes Field has been used for refuelling aircraft bound for Europe, and more recently, the Middle East. The United States Navy operates a small fleet of military ships in the harbour of Praia da Vitória, three kilometres (2 mi) southeast of Lajes Field. The airfield also has a small commercial terminal handling scheduled and chartered passenger flights from other islands in the archipelago, Europe, and North America. In 1976, the Azores became the Autonomous Region of the Azores (Região Autónoma dos Açores), one of the Autonomous regions of Portugal, and the Azorean districts were suppressed.