The origins of route 3 lie in separate tram lines. The section of track between Queensberry Street (Stop 4) and Brighton Road (Stop 35) is the oldest section of this route, dating back to the Brighton Road cable tram which opened on 11 October 1888 by the Melbourne Tramway & Omnibus Company. This cable tram line was electrified in stages by the Melbourne & Metropolitan Tramways Board (MMTB). The section between Domain Interchange (Stop 20) and St Kilda Junction (Stop 30) was electrified on 27 December 1925. The section between Queensberry Street and City Road (near Stop 14) was electrified on the same day. The line between City Road and Domain Interchange was electrified on 24 January 1926, and the line between St Kilda Junction and Carlisle Street (Stop 35) was finally electrified on 29 August 1926.