San Nicolás de los Arroyos Partido is the northernmost partido in Buenos Aires Province, Argentina. The provincial subdivision has a populatio…San Nicolás de los Arroyos Partido is the northernmost partido in Buenos Aires Province, Argentina. The provincial subdivision has a population of about 200,000 inhabitants in an area of 1,183 km², and its capital city is San Nicolás de los Arroyos, which is around 221 km from Buenos Aires.