Buenos Aires, officially the Buenos Aires Province, is the largest and most populous Argentine province. It takes its name from the city of Buenos Aires, the capital of the country, which used to be part of the province and the province's capital until it was federalized in 1880. Since then, in spite of bearing the same name, the province does not include Buenos Aires city, though it does include all other parts of the Greater Buenos Aires metropolitan region, which include approximately three-fourths of the conurbation's population. The capital of the province is the city of La Plata, founded in 1882.
It is bordered by the provinces of Entre RÃos to the northeast, Santa Fe to the north, Córdoba to the northwest, La Pampa to the west, RÃo Negro to the south and west and the Autonomous City of Buenos Aires to the northeast. Uruguay is just across the Rio de la Plata to the northeast, and both are on the coast of the Atlantic Ocean to the east. Almost the entire province is part of the Pampas geographical region, with the extreme south often considered part of the Patagonia region.