Rosario (rôsärˈyō) [key], city (1991 pop. 1,095,906), Santa Fe prov., E central Argentina, a port on the Paraná River, on the eastern margin of the Pampa. The third largest city of Argentina, it is primarily the import and export center for the central and northern provinces. Steel, cars, and farm machinery are the principal manufactures. It also exports grains, beef, and wood products. Rosario is the terminus of several railroads and has excellent port facilities. It was settled in the late 17th cent. but grew mainly after 1870 with the rapid development of the Pampa. It has a small airport.