From Ethnologue (http://www.ethnologue.com/language/tsn):
Alternate Names: Beetjuans, Chuana, Coana, Cuana, Sechuana, Setswana
Population: 1,070,000 in Botswana (Johnstone 1993). 3,410,000 in South Africa (2006). Population total all countries: 4,521,700.
Location: Widespread as lingua franca; Southeast and Kgatleng districts; east Southern and Kweneng districts, Central District, Serowe-Palapye and Mahalapye subdistricts; Northwest District Maun village area. Also in Namibia, South Africa, Zimbabwe.
Language Status: De facto national language in Botswana. Statutory national language in South Africa (1996, Constitution, Article 6(1)).
Classification: Niger-Congo, Atlantic-Congo, Volta-Congo, Benue-Congo, Bantoid, Southern, Narrow Bantu, Central, S, Sotho-Tswana (S.31)
Dialects: Kgatla, Kwena, Lete, Ngwaketse, Ngwatu (Ngwato), Rolong, Sehurutshe, Tawana, Tlahaping (Tlapi), Tlokwa. High intelligibility among Southern Sotho [sot], Northern Sotho [nso], and Tswana. Standard Tswana is based on the Sehurutshe dialect and is nearly identical to it.
Language Use: Vigorous. 150,000 L2 speakers. Used among the educated. More for spoken purposes than written. All ages.
Language Development: Literacy rate in L1: 80%–90%. Official language of instruction grades 1–4 in all government primary schools. Taught in primary schools. Magazines. Newspapers. New media. Radio programs. TV. Dictionary. Grammar.
Writing: Latin script.