The Po Valley, Po Plain, Plain of the Po, or Padan Plain is a major geographical feature of Northern Italy. It extends approximately 650 km (400 mi) in an east-west direction, with an area of 46,000 km² including its Venetic extension not actually related to the Po river basin; it runs from the Western Alps to the Adriatic Sea. The flatlands of Veneto and Friuli are often considered apart since they do not drain into the Po, but they effectively combine into an unbroken plain, making it the largest in Southern Europe. It has a population of 17 million, or a third of Italy's total population.