city, Harford county, northeastern Maryland, U.S., near Chesapeake Bay, 26 miles (42 km) northeast of Baltimore. Settled about 1800, it was named for the city in Scotland. Aberdeen is the principal trading centre for the nearby 113-square-mile (293-square-km) Aberdeen Proving Ground (established 1917), a U.S. Army test site for guns, ammunition, and military vehicles; one of the world's largest collections of weapons is displayed there in the U.S. Army Ordnance Museum. There is also some light manufacturing. Inc. town, 1892; city, 1992. Pop. (1990) 13,087; (2000) 13,842.

Aberdeen originated as two separate burghs: Old Aberdeen, the cathedral and university settlement on the Don, and New Aberdeen, the neighbouring trading and fishing village on the Dee. Old Aberdeen, reputedly founded in 580 by St. Machar, a disciple of the Celtic missionary St. Columba, became the seat of the bishopric of Aberdeen and was virtually destroyed by the English in 1336. The present St. Machar's Cathedral, begun in 1424, is a fortified granite building. Royal charters of 1489 and 1498 created a “free burgh” with the church as its administrator. Remnants of this ecclesiastical power survived until 1891, when the episcopal burgh was incorporated with New Aberdeen to form the present city. The oldest surviving charter (1179) confers several trade privileges on the burgesses of Aberdeen.

Some of the oldest streets, from the 13th and 14th centuries, survive near the Castlegate, the historic marketplace of New Aberdeen and commercial heart of the modern city. The Castlegate still contains an old Market (City) Cross (1686). Nearby are two ancient houses, Provost Skene's House (c. 1545), now a local history museum, and Provost Ross's House (1593). The parish church of St. Nicholas (Union Street) is divided into two parts: the West Church (built in 1755 by James Gibbs) is separated from the East Church (built in 1838 by Archibald Simpson) by the original 13th-century transept and 19th-century steeple. Two medieval bridges have survived, the Brig o' Balgownie (1320), spanning the Don, and the Old Bridge of Dee (1527). Other significant buildings include several modern municipal buildings, the Music Hall (1822; Neoclassical), and Marischal College (Broad Street), reputedly the world's largest granite building, begun in 1844 by Archibald Simpson.

The University of Aberdeen was formed in 1860 by the union of two medieval colleges: King's College, founded as a Roman Catholic institution in 1495, and the Protestant Marischal College, founded in 1593. Other educational institutions include the Robert Gordon University (founded as Robert Gordon Hospital, 1750), Aberdeen College, and the Scottish Agricultural College, and there are research institutes for fisheries (Marine Laboratory Aberdeen), soil science (Macaulay Land Use Research Institute), and animal nutrition (Rowett Research Institute). Aberdeen's old Grammar School was a medieval foundation.

Aberdeen is an important transport centre by road, rail, sea, and air. The original harbour, the Dee estuary, has been continually improved. It was Scotland's premier fishing port from the introduction of steam trawling until the rise of the North Sea oil industry. Today it is the chief port of northern Scotland, trading mainly with Scandinavia and the Baltic. Typical port industries—chemicals, fertilizers, and engineering, as well as Britain's largest granite-exporting industry—exist alongside a flourishing tourist industry. The North Sea oil boom of the late 20th century benefited Aberdeen more than any other city of Scotland, bringing more than 200 new companies and thousands of new foreign residents and financing the construction of housing, offices, and schools. Some 800 acres (324 hectares) of industrial land were allocated to attract industry associated with oil technology. Area 71 square miles (184 square km). Pop. (2006 est.) 206,880.

city, seat (1880) of Brown county, northeastern South Dakota, U.S. It lies in the James River valley about 160 miles (260 km) northeast of Pierre. Established in 1881 as a junction of several railroads, it was named for Aberdeen in Scotland by Alexander Mitchell, president of the Chicago, Milwaukee, and St. Paul Railroad (Chicago, Milwaukee, St. Paul and Pacific Railroad Company). Aberdeen is in the state's most productive agricultural region, producing cattle, hogs, sheep, soybeans, corn (maize), wheat, barley, rye, hay, and sunflowers. The city's economy has now diversified to include manufacturing (medical supplies, power transmission equipment, machine tools, and missile components) and services (travel services, agricultural marketing, and financial collection). Aberdeen is a health care, trade, and commercial centre for a large region. Tourism, based on fishing and hunting (particularly during the autumn pheasant-hunting season), augments the economy. Aberdeen is home to Northern State University (1901) and Presentation College (1951). The Dacotah Prairie Museum preserves regional history. Authors Hamlin Garland (Garland, Hamlin), known for his autobiographical Middle Border series, and L. Frank Baum (Baum, L. Frank), who wrote The Wonderful Wizard of Oz (1900), lived in Aberdeen. The annual Oz Festival (June) commemorates Baum, his work, and his time in Aberdeen. Sand Lake National Wildlife Refuge (northeast) and Richmond Lake (northwest) and Mina Lake (west) recreation areas are nearby. Inc. town, 1882; city, 1883. Pop. (1990) 24,927; (2000) 24,658.

city, Grays Harbor county, western Washington, U.S., on the Pacific estuaries of the Chehalis, Wishkah, and Hoquiam rivers (which together form Grays Harbor). With Hoquiam and Cosmopolis, Aberdeen forms a tri-city area. Captain Robert Gray (Gray, Robert) navigated the inlet in the ship Columbia on May 7, 1792, and named it Bullfinch Harbour. In 1878 settler Samuel Benn laid out a village, which 10 years later merged with the adjacent settlement of Wishkah to form the town of Aberdeen. A Northern Pacific Railway (Northern Pacific Railway Company) line reached the city in 1895 after residents donated their labour to build a branch, giving Aberdeen an economic advantage over its larger neighbours; it grew to become the commercial and industrial centre of the area. A fire devastated the downtown district in 1904; afterward most of the city's buildings were made of brick rather than wood. Fishing, lumbering, seafood processing, and tourism are its economic mainstays. The deepwater port of Grays Harbor is midway between Aberdeen and Hoquiam. The two-year Grays Harbor College was founded at Aberdeen in 1930. Inc. city, 1890. Pop. (1990) 16,565; (2000) 16,461.