Cobb & Co's operations across Australia were eventually superseded by the expansion of railway networks, the arrival of cheap, reliable automobiles and the emergence of air mail. In 1920, the Charleville coachworks closed and by 1921, Cobb & Co in Queensland had lost most of its mail contracts running out of Charleville. The company also had a vast amount of debt due to over-expansion into industries like wool. Rutherford had died in 1911 the same year the Company approved its first purchase of motor vehicles. In New South Wales the last coach probably ran on the Hebel-Goodooga-Brewarrina routes in 1913 while the last coach ran in Victoria from Casterton to Mount Gambier in 1916. Australia's last horse-drawn stagecoach service was run by Cobb & Co from Yuleba to Surat in Queensland on 14 August 1924. With the rapid decline in wool prices in 1929, Cobb & Co Queensland finally went into liquidation.