SOLOTHURN (Fr. Soleure), a canton in north-west Switzer land; total area (1923-24) is 305.5 sq.m., of which 96.7% are reckoned as productive. This is higher than for any other Swiss canton. Solothurn has a most irregular shape, dependent on the fact that the canton consists of territories won at different dates by the town from which it takes its name. It includes an area of plain along the Aar valley projecting into Canton Berne, with the Bucheggberg in the southwest between the Aar and Emme, a right-bank tributary joining the larger river near the town of Solothurn. Farther downstream, a part of the Aar valley belongs to Berne, but Solothurn resumes possession somewhat later and here the Aar receives the Wigger on the right bank at Aarburg, and the Dunneran from the Jura on the left bank at Olten. This section of the canton may be described as the foot of the Jura. The Hasenmatt ft.) is the highest point of the Weissenstein section of the main Jura range which runs through the country north of the capital. Across this range, Solothurn stretches in a broad belt to the north where, at various points, it shares with Berne the river Birs, a tributary flowing into the Rhine near Basle. Beyond the Birs, are two separated districts belonging to the canton : Hofstetten, including the famous pil grimage centre Mariastein, and Kleinliitzel. The north part of the canton and its detached fragments touch the cantons of Berne and Basleland. Highroad and railway communica tions are excellent. Olten is a great railway junction where the direct lines from the St. Gotthard via Lucerne, from Geneva, from Zurich, and from Basle all unite. Formerly various districts were in the dioceses of Lausanne, Basle and Constance, but since 1814 they have all ranked as part of the diocese of Basle, with the town of Solothurn as the site of the bishop's palace. In 1920 the population was 130,617, of whom 125,183 were German speaking, 2,621 French-speaking and 2,514 Italian-speaking; 81,989 were Catholics, Protestants and 163 Jews. The capital is Solo
thurn (13,756 pop. in 1930), and the only other fairly large town is Olten (13,555), both on the Aar. Between Solothurn and the small industrial town of Grenchen, to the west-south-west, lies the village of Selzach, noted for its annual passion-play. The pop. (1930) was were Protestant, 87,087 Catholic.
Till about 1850 the cantonal activities were mainly agricultural and pastoral, and though these are still important, yet its density of population (433 per sq.m. in 1920, against 243 for Switzer land as a whole), is largely dependent on the variety of its manu factures, e.g., watches, jewellery, shoes, cotton, motor parts and cement, particularly around Solothurn and Grenchen.
Soleure is divided into ten administrative districts with 132 communes. The cantonal Constitution dates from 1887, but was substantially revised in 1895. The Kantonsrat, or legislative as sembly, is now elected according to the principles of proportional representation. The 130 deputies are chosen on the basis of one member for each r,000 of the total resident population in 1920. The Regierungsrat or executive consists of five members. Both groups hold office for four years, but any 4,000 citizens can de mand a popular vote on Abberufung, or recall, to decide as to whether the existing members shall continue to sit or not. In addi tion, the "obligatory referendum" and the "initiative" exist. By the former, since 1869, all laws and financial resolutions passed by the Kantonsrat must be approved by a popular vote. By the latter, since 1869, 2,000 electors can compel the legislative assembly to consider any legislative proposal. Further, since 1856, the demand of electors is to necessitate a popular vote as to the advisability of effecting some constitutional change. The two members of the federal Standerat and the seven members of the federal Nationalrat are also chosen by a popular vote.