What is Australia's newest State or Territory?

Answer 1

Both of Australia's mainland territories, the ACT or the Australian Capital Territory and the Northern Territory, were established in 1911. The ACT was established purely for the purpose of setting aside land for the country's new capital, while the Northern Territory was initially part of South Australia, and only referred to Commonwealth control in 1911.

All of Australia's external territories (Ashmore and Cartier Islands, Christmas Island, the Cocos (or Keeling) Islands, the Coral Sea Islands, Heard Island, Jervis Bay, the McDonald Islands, Macquarie Island, Norfolk Island and the Australian Antarctic Territory) were acquired later than 1911.