Ain, a department of France in Burgundy, bounded by Saone-et-Loire, Jura, Switzerland, Haute-Savoie, Savoie, Isere, and Rhone; area, 2,239 sq. m.; pop. in 1872, 336,290. The Rhone flows on its eastern and southern borders, and the Saone on the western. The eastern section of the department is traversed by mountain ranges and deep valleys. The western division is low, level, and swampy, and dotted with numerous ponds. The river Ain, an affluent of the Rhone, flows through the centre, and has many saw and grist mills on its banks. Immense rafts of timber are floated down its rapid current to Lyons. The products of the department are chiefly agricultural. Sheep are reared in great numbers in the eastern part. It is divided into the arrondisse-ments of Bourg, Belley, Nantua, Trevoux, and Gex. Capital, Bourg-en-Bresse.