AARGAU, ar′gŏw (“Aar-shire”: Fr. Argovie, ar-gō-vē), Switzerland, an extreme N. canton between Basel W., Zurich E., Lucerne S., and the Rhine and Baden G. Area 542 square miles; capital, Aarau. It consists mainly of spurs of the Alps and Jura, nowhere over 3,000 feet above sea-level, with numerous fertile valleys watered by the Aar and its S. E. tributaries, the Limmat (or Linth) and Reuss (see Aar) being chief. The climate is moist and variable, and stock-farming and agriculture are advanced: fruit, vegetables, and vines abound, but the wines are inferior. Timber is plentiful. Manufactures: cottons, silks, ribbons, linens, hosiery, straw-plait, etc., and important machine works. The boat traffic on the Aar and Rhine, and the active land and water transit trade, employ many. It has several picturesque ruined castles. Aargau, part of old Helvetia, then conquered by the Franks (5th century), a Hapsburg fief 1173–1415, then captured by the Cantonal League and divided between Bern and Lucerne, was split up and a part made a member of the Helvetic Republic 1798. Its constitution was first fixed by the Congress of Vienna in 1815; in 1831 it gained a democratic one, and has ever since been a champion of liberalism. In 1841 it suppressed its eight monasteries, and this led to the formation of the Sonderbund (q. v.), or Secession League, of Catholic cantons in 1847. Legislative power is vested in the Great Council, one for every 1,100 people, which has to submit laws and decrees to a referendum; executive power in the Small Council of five, chosen by and from the Great one. Aargau sends 10 members to the National Council. Pop. (1913) 236,860, nearly all German. See Switzerland and consult Hierli, J., ‘Die archäologische Karte des Kantons Aargau’ (Aaran 1899); Zschokke, E., ‘Geschichte des Aargaus’ (ib., 1903), and ‘Historische Gesellschaft des Kantons Aargau’ (ib., 1898).