The Commonwealth Electoral Division of Barker covers the area from Morgan in the North to Port MacDonnell in the south. The eastern boundary is the South Australian border. It includes the Upper and Lower South East, the Mallee, the Riverland, the Murraylands and most of the Barossa Valley.
Towns include Barmera, Berri, Bordertown, Keith, Kingston SE, Loxton, Mannum, Millicent, Mount Gambier, Murray Bridge, Naracoorte, Nuriootpa, Penola, Renmark, Tanunda, Tailem Bend, and Waikerie