The passing of the
Main Roads Act of 1924 through the
Parliament of New South Wales provided for the declaration of Main Roads, roads partially funded by the State government through the
Main Roads Board (MRB, later
Transport for NSW).
Mid-Western Highway was declared (as Main Road No. 6) on 8 August 1928, from the interchange with
Great Western Highway and North-Western Highway (today
Mitchell Highway) in Bathurst, via Blayney, Cowra,
Wyalong,
Rankins Springs,
Gunbar,
Booligal,
Oxley,
Balranald,
Euston, and
Wentworth, to the border with South Australia beyond
Lake Victoria; to provide for additional declarations of State Highways and Trunk Roads, this was amended to State Highway 6 on 8 April 1929. The highway was rerouted between Gunbar and Balranald to pass through Hay on 24 September 1929. The
Department of Main Roads, which had succeeded the MRB in the previous year, proclaimed the portion of the highway between Hay via Euston and Wentworth to the South Australian border to be part of
Sturt Highway on 8 August 1933; the highway's western end was truncated at its own junction with Sturt Highway at Hay instead. This was further altered when State Highway 21 (later
Cobb Highway) was altered to run through Hay on 12 January 1944; Mid-Western Highway was further truncated to the intersection with State Highway 21 in Hay as a result. Newell Highway was declared a National Highway in 1992, and was re-declared to form one continuous highway on 15 January 1993: as a consequence, Mid-Western Highway was re-declared to run from Hay to West Wyalong, and then from Marsden to Bathurst. The passing of the
Roads Act of 1993 updated road classifications and the way they could be declared within New South Wales. Under this act, Mid-Western Highway today retains its declaration as Highway 6, from Hay via Goolgowi and Rankin Springs to the intersection with Newell Highway at West Wyalong, then from the intersection of Newell Highway at Marsden via Grenfell and Cowra to Bathurst. Mid-Western Highway was signed National Route 24 across its entire length in 1955. With the conversion to the newer alphanumeric system in 2013, this was replaced with route A41 between Bathurst and Cowra, and route B64 between Cowra and Hay. ==Major intersections==