South Australia (commonly abbreviated as SA) is a state in the southern central part of Australia. 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, which includes some of the most arid parts of the continent, and with 1.8 million people it is the fifth-largest of the states and territories by population. This population is the second-most highly centralised in the nation 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.