Mannum is a historic town on the west bank of the Murray River in South Australia, 84 kilometres (52 mi) east of Adelaide. Mannum is the seat of the Mid Murray Council, and is situated in the state electoral district of Hammond and the federal Division of Barker.

The Division of Barker is an Australian electoral division in the south-east of South Australia. The division was established on 2 October 1903, when South Australia's original single multi-member division was split into seven single-member divisions. It is named for Collet Barker, an early explorer of the region at the mouth of the Murray River. The 63,886 km² seat currently stretches from Morgan in the north to Port MacDonnell in the south, taking in the Murray Mallee, the Riverland, the Murraylands and most of the Barossa Valley, and includes the towns of Barmera, Berri, Bordertown, Coonawarra, Keith, Kingston SE, Loxton, Lucindale, Mannum, Millicent, Mount Gambier, Murray Bridge, Naracoorte, Penola, Renmark, Robe, Tailem Bend, Waikerie, and parts of Nuriootpa and Tanunda.