Politically, almost all of Silesia is divided between Poland and the Czech Republic. The Polish portion comprises most of the former Prussian provinces of Upper Silesia and Lower Silesia, both of which were transferred to Polish administration at the Potsdam Conference of 1945; the Polish portion also includes those parts of Upper Silesia that were ceded by Germany to Poland after World War I and part of the former Austrian principality of Teschen. A second, much smaller part of Silesia belonged to Czechoslovakia since 1918, and became part of the Czech Republic with the dissolution of Czechoslovakia in 1993.
Except in the south, Silesia is largely an agricultural and forested lowland, drained by the Oder and its tributaries. The major city of the region is Wrocław. Along the slopes of the Sudetes there are numerous small industrial centers with traditional textile and glass industries. Czech Silesia comprises the rich Karvinna coal basin. The most important part of Silesia is, however, its southern tip—Upper Silesia, in Poland. One of the largest industrial concentrations of Europe, it has extensive coal and lignite deposits and zinc, lead, iron, and other ores. The industrial area around Katowice comprises such important centers as Bytom, Gliwice, Zabrze, and Częstochowa, and has iron and steel mills, coke ovens, and chemical plants. Opole, the former capital of Upper Silesia, is an important trade center.