Officially Argentine Republic, republic (2005 est. pop. 39,538,000), 1,072,157 sq mi (2,776,889 sq km). Argentina occupies most of southern South America. The country is bounded by the Andes Mountains in the west, and slopes gently downhill. Capital city Buenos Aires. Area 2,766,890 sq km (1,068,296 sq miles) Population 38,400,000 Official language Spanish.