It was not until the advent of automobiles that a route through the steep Cunningham's Gap became feasible. The original road was built entirely by voluntary labour and Acting Queensland Premier, William Forgan Smith, officially opened on 11 June 1927, the 100-year anniversary of Allan Cunningham's supposed discovery of Cunningham's Gap. Actually, Cunningham discovered two gaps, Spicer's Gap on 11 June 1827 as he approached from the Darling Downs side and Cunningham's Gap on 21 August 1828 as he approached from Ipswich. However, Cunningham mistakenly believed he had found both sides of the same gap and not two different ones. This mistake was then perpetuated on the monument to Cunningham unveiled as part of the official opening of the road, as it gave 11 June 1827 as the discovery of Cunningham's Gap.