Glenelg Highway is a rural highway in south-eastern Australia, linking the major regional centres of Mount Gambier in south-eastern South Australia with Ballarat in western Victoria.

[6] Glenelg Highway commences at the intersection with Princes Highway in Glenburnie, South Australia and heads on a north-easterly direction as a two-lane, single carriageway rural highway, crossing the interstate border into Victoria 15km later (some maps identify the South Australian section as Casterton Road), continuing northeast to Casterton, then heading in an easterly direction through the towns of Hamilton, Dunkeld and Skipton, before eventually terminating at the intersection with Midland Highway in the south-eastern suburb of Sebastopol in Ballarat.

[13] The passing of the Highways and Vehicles Act of 1924[14] provided for the declaration of State Highways, roads two-thirds financed by the State government through the Country Roads Board.

[16] A new bridge over Hopkins River in Wickcliffe was opened in 1996, replacing an older, flood-prone structure and the last on the highway with a timber deck, at a cost of $145,000, with bridge approaches costing $700,000.

The passing of the Road Management Act 2004[18] granted the responsibility of overall management and development of Victoria's major arterial roads to VicRoads: in 2004, VicRoads re-declared the road as Glenelg Highway (Arterial #6670), beginning at the South Australian border and ending at Midland Highway in Sebastopol, Ballarat.