Cape Verde independence for the archipelago in 1975. Following the April 1974 revolution in Portugal, the PAIGC became an active political movement in Cape Verde. In December 1974, the PAIGC and Portugal signed an agreement providing for a transitional government composed of Portuguese and Cape Verdeans. On 30 June 1975, Cape Verdeans elected a National Assembly which received the instruments of independence from Portugal on 5 July 1975. In the late 1970s and 1980s, most African countries prohibited South African Airways from overflights but Cape Verde allowed them and became a centre of activity for the airline's flights to Europe and the
Boa Vista, Cape Verde salt deposits, which were mainly exploited by the English. In 1820, after many pirate attacks, the population moved to Porto Inglês, later renamed Sal Rei, which had been founded at the end of the 18th century. As did much of the Cape Verdean economy, the exploitation of salt on Boa Vista also relied largely on slavery. A Portuguese-British commission to end slavery was established in Boa Vista in 1842, but slavery was not completely abolished until 1876. Until 1935 the municipality of Boa Vista also covered the island of Sal. In 1975, Cape Verde declared its independence. Administratively, the island