AARGAU (Fr. Argovie), one of the more northerly Swiss cantons, comprising the lower course of the river Aar (q.v.), whence its name. Its total area is 541·9 sq. m., of which 517·9 sq. m. are classed as “productive” (forests covering 172 sq. m. and vineyards 8·2 sq. m.). It is one of the least mountainous Swiss cantons, forming part of a great table-land, to the north of the Alps and the east of the Jura, above which rise low hills. The surface of the country is beautifully diversified, undulating tracts and well-wooded hills alternating with fertile valleys watered mainly by the Aar and its tributaries. It contains the famous hot sulphur springs of Baden (q.v.) and Schinznach, while at Rheinfelden there are very extensive saline springs. Just below Brugg the Reuss and the Limmat join the Aar, while around Brugg are the ruined castle of Habsburg, the old convent of Königsfelden (with fine painted medieval glass) and the remains of the Roman settlement of Vindonissa [Windisch]. The total population in 1900 was 206,498, almost exclusively German-speaking, but numbering 114,176 Protestants to 91,039 Romanists and 990 Jews. The capital of the canton is Aarau (q.v.), while other important towns are Baden (q.v.), Zofingen (4591 inhabitants), Reinach (3668 inhabitants), Rheinfelden (3349 inhabitants), Wohlen (3274 inhabitants), and Lenzburg (2588 inhabitants). Aargau is an industrious and prosperous canton, straw-plaiting, tobacco-growing, silk-ribbon weaving, and salmon-fishing in the Rhine being among the chief industries. As this region was, up to 1415, the centre of the Habsburg power, we find here many historical old castles (e.g. Habsburg, Lenzburg, Wildegg), and former monasteries (e.g. Wettingen, Muri), founded by that family, but suppressed in 1841, this act of violence being one of the main causes of the civil war called the “Sonderbund War,” in 1847 in Switzerland. The cantonal constitution dates mainly from 1885, but since 1904 the election of the executive council of five members is made by a direct vote of the people. The legislature consists of members elected in the proportion of one to every 1100 inhabitants. The “obligatory referendum” exists in the case of all laws, while 5000 citizens have the right of “initiative” in proposing bills or alterations in the cantonal constitution. The canton sends 10 members to the federal Nationalrat, being one for every 20,000, while the two Ständeräte are (since 1904) elected by a direct vote of the people. The canton is divided into eleven administrative districts, and contains 241 communes.
In 1415 the Aargau region was taken from the Habsburgs by the Swiss Confederates. Bern kept the south-west portion (Zofingen, Aarburg, Aarau, Lenzburg, and Brugg), but some districts, named the Freie Ämter or “free bailiwicks” (Mellingen, Muri, Villmergen, and Bremgarten), with the county of Baden, were ruled as “subject lands” by all or certain of the Confederates. In 1798 the Bernese bit became the canton of Aargau of the Helvetic Republic, the remainder forming the canton of Baden. In 1803, the two halves (plus the Frick glen, ceded in 1802 by Austria to the Helvetic Republic) were united under the name of Kanton Aargau, which was then admitted a full member of the reconstituted Confederation.
See also Argovia (published by the Cantonal Historical Society), Aarau, from 1860; F. X. Bronner, Der Kanton Aargau, 2 vols., St Gall and Bern, 1844; H. Lehmann, Die aargauische Strohindustrie, Aarau, 1896; W. Merz, Die mittelalt. Burganlagen und Wehrbauten d. Kant. Argau (fine illustrated work on castles), Aarau, 2 vols., 1904–1906; W. Merz and F. E. Welti, Die Rechtsquellen d. Kant. Argau, 3 vols., Aarau, 1898–1905; J. Müller, Der Aargau, 2 vols., Zürich, 1870; E. L. Rochholz, Aargauer Weisthümer, Aarau, 1877; E. Zschokke, Geschichte des Aargaus, Aarau, 1903. (W. A. B. C.)