canton, northwestern Switzerland. It is bounded by the cantons of Bern to the west and south, Jura to the west, Aargau to the east, and Basel-Landschaft (demicanton) to the north. It is drained by the Aare River and its tributaries. Consisting of territories acquired by Solothurn (q.v.), its capital city, from which it took its name, it has an irregular shape, including two completely detached districts bordering on France in the north. It also includes the foothills of the Jura Mountains and a plain along the Aare River valley, part of which extends into Bern canton.
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