ORURO, a department and town of Bolivia. The department is bounded N. by La Paz, E. by Cochabamba and Potosí, S. by Potosí, and W. by Chile; it forms a part of the ancient Titicaca lacustrine basin, and has an area of 19,127 sq. m., the greater part of which is semi-arid and covered with extensive saline deposits. It is bordered by Cordilleras on the E. and W., and by transverse ridges and detached groups of elevations on the N. and S. The slope and drainage is toward the S., but many of the streams are waterless in the dry season. The outlet of Lake Titicaca, the Desaguadero river, flows southward into Lake Pampa-Aullaguas, or Poöpo, on the eastern side of the department near the Cordillera de los Frailes. Lake Pöpo is 12,139 ft. above sea-level, or 506 ft. lower than Titicaca, and its waters discharge through a comparatively small outlet, called the Lacahahuíra, into the lagoon and saline morasses of Coipasa (12,057 ft. elevation) in the S.W. corner of the department. Oruro is almost exclusively a mining department, the country being too arid for agriculture, with the exception of a narrow strip in the foothills of the Cordillera de los Frailes, where a few cattle, mules and llamas, and a considerable number of sheep are reared. The mineral wealth has not been fully developed except in the vicinity of the capital, in the north-east part of the department, where there are large deposits of tin, silver and copper, Oruro being the second largest producer of tin in the republic. There are borax deposits in the western part of the department, but the output is small.

The capital of the department is Oruro, 115 m. S.S.E. (direct) of La Paz; it is an old mining town dating from the 17th century, when it is said to have had a population of 70,000. The census of 1900 gave it a population of 13,575, the greater part of whom are Indians. A considerable number of foreigners are interested in the neighbouring mines. The elevation of Oruro is 12,250 ft. above sea-level, and its climate is characterized by a short cool summer and a cold rainy winter, with severe frosts and occasional snow-storms. The mean annual temperature is about 43 F. Oruro is the Bolivian terminus of the Antofagasta railway (0.75 metre gauge), 574 m. long, the first constructed in Bolivia. A law of the 27th of November 1906 provided for the construction of other lines, of metre gauge, from La Paz (Viacha) to Oruro, from Oruro to Cochabamba, and from Oruro to Tupiza, making Oruro the most important railway centre in Bolivia. Oruro enjoys the nominal distinction of being one of the four capitals of the republic, an anomaly which was practically ended by the revolution of 1898, since which time the government has remained at La Paz.