Aden (ä´dən, ā´dən), city (1994 pop. 398,399), SW Yemen, on the Gulf of Aden near the southern entrance to the Red Sea. It is the chief port of Yemen. Aden consists of two peninsulas, Aden and Little Aden, and an intervening stretch of the mainland. Each peninsula has a high volcanic headland (Aden rises to 1,742 ft/531 m, and Little Aden to 1,147 ft/350 m), which is linked to the mainland by a flat, sandy isthmus. The bay between the peninsulas is an excellent harbor. Aden peninsula contains most of the city's population and is divided into a number of districts that were once towns. Wells near Sheikh Othman, on the mainland, supply the city with water. Little Aden peninsula has the city's main industrial district and is the site of a large oil refinery; the manufacture of soap, cigarettes, and salt is also important.
Aden, a free port since 1850, has been the chief entrepôt and trading center of S Arabia since ancient times. It enjoyed commercial importance until the discovery (late 15th cent.) of an all-water route around Africa to India. With the opening of the Suez Canal (1869), Aden regained its importance and again became a major trading center and also an important refueling stop; the harbor was deepened to accommodate the largest vessels able to use the canal. Aden's economy, which depends heavily on canal traffic, suffered from the closing of the canal during and after the 1956 and 1967 Arab-Israeli wars.
Aden's strategic location and its importance as a commercial center long made it a coveted conquest. Muslim Arabs held the region from the 7th to the 16th cent. The Portuguese failed in an attempt to capture it in 1513, but it fell in 1538 to the Ottoman Turks. At the end of the 18th cent. Aden's importance as a strategic post grew as a result of British policy to contain French expansion in the region. After the British capture of Aden in 1839, its administrative attachment to India, and the construction of the Suez Canal, Britain purchased areas on the mainland from local rulers and entered into protectionist agreements with them. The Perim, Kamaran, and Kuria Muria islands had been made part of Aden in the 1850s. Aden was formally made into a crown colony in 1937, and the surrounding region became known as the Aden Protectorate in 1937.
Aden was granted a legislative council in 1944 and later received other rights of self-government. In 1963 Aden was joined to the Federation of the Emirates of the South, which then became the Federation of South Arabia (see South Arabia, Federation of). With the establishment (1967) of the independent country of Southern Yemen, Aden became the capital along with Madinat ash Shab. In 1970 Aden became the country's sole capital. In 1990 Southern Yemen and Yemen united to form one country, Yemen. Sana became capital of the new nations, and Aden was designated its economic capital. The city was severely damaged during the 1994 Yemeni civil war.
See G. King, Imperial Outpost, Aden (1964); J. Paget, Last Post: Aden, 1964–67 (1969); R. F. Nyrop, Yemens: Country Studies (1986).