Stretching some 90 miles from the eastern side of Hampshire through to East Sussex, there have been plans to designate the South Downs as a National Park since 1947.
The South Downs landscape attracts about 39 million visitors every year and is renowned for its rolling chalk uplands, river valleys and woodland.
The area was protected by two Areas of Outstanding Natural Beauty but campaigners said the National Park status would bring added protection and help enhance its beauty for generations to come.
The area includes the Seven Sisters - chalk cliffs that run from Seaford towards Eastbourne which are being eroded by the sea.
The bottom of the cliffs at Seven Sisters are exposed to the sea as the tide comes in and out, scouring channels and gulleys.
Supporters of the national park campaign have said the South Downs represents the "green lung" of the South East, containing some of the most admired hill country in Britain.
Celebrities who backed the fight for a South Downs national park include author Bill Bryson, presenters Ben Fogle, Floella Benjamin OBE, David Dimbleby and actor Brian Blessed.