South Australia is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of 984,321 square kilometres, it is the fourth-largest of Australia's states and territories by area, and it is second-smallest state by population. It has a total of 1.8 million people. Its population is the second-most highly ce…South Australia is a state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of 984,321 square kilometres, it is the fourth-largest of Australia's states and territories by area, and it is second-smallest state by population. It has a total of 1.8 million people. Its population is the second-most highly centralised in Australia, after Western Australia, with more than 77% of South Australians living in the capital Adelaide, or its environs. Other population centres in the state are relatively small; Mount Gambier, the second-largest centre, has a population of 26,878.