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 (380,048 sq mi), it is the fourth-largest of Australia's states and territories by area, and 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 percent 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.