Although the Queensland branch of the company made an effort to transition to automobiles in the early 20th century, high overhead costs and the growth of alternative transport options for mail, including rail and air, saw the final demise of Cobb & Co.

[2] Parallels may be drawn between Australia's Cobb & Co and America’s Wells Fargo stagecoach services, both of which played similar and important roles in their respective countries' histories.

With financial support from another newly arrived US businessman George Train, they arranged the importation of several US-built wagons and Concord stagecoaches.

[1][3][4] Cobb & Co's horses were changed at stages every 10–15 miles along a stagecoach "line" often at inns or hotels that could also cater for the needs of drivers and passengers.

Their imported Concord stagecoaches used thorough-brace technology, on which thick straps of leather suspended the body of the vehicle, providing passengers with greater comfort on the rough country roads when compared to coaches with traditional steel-springs.

Built in Ballarat by Morgan's coach works, "Leviathan" could accommodate up to sixty passengers and was drawn by a team of eight horses.

[7] In June 1862, Rutherford oversaw the extension of the business into New South Wales following news of the Lambing Flat gold rush.

Rutherford moved ten coaches from Bendigo to Bathurst with great publicity to announce and establish Cobb & Co's presence.

[1] Rutherford established a Cobb & Co buggy and coachworks in Bathurst, and the firm also began to invest in properties — the first being "Buckiinguy" station near Nyngan, New South Wales.

[1] In 1871, the formal links between the Victorian Cobb & Co (taken over by Robertson and Wagner) and Rutherford's New South Wales and Queensland operation were finally dissolved, although harmonious relations continued.

In time, successive operators of the various Victorian stagecoach lines would continue to use the trading name Cobb & Co.[5] In the 1870s, the fare for the 460km journey from Dalby to Roma in Queensland, was about £5 per day with an additional two shillings and sixpence (£-/2/6) for each meal and bed.

The nationalistic art, music and writing of late 19th-century Australia romanticized a pioneering rural or "bush myth"[19] and Cobb & Co with its colourful drivers and managers easily fell into this tradition.

Everingham notes that Cobb & Co's expansion into New South Wales coincided with an increase in the number of armed hold-ups by bushrangers.

"[22] 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.

Following a legal case and settlement with Studdert, the Cobb & Co name was acquired by the Redmans Transport company of Toowoomba, run by Bill Bolton MBE (1905–1973).

It included a re-enactment of the last stagecoach journey from Surat to Yuleba using a replica Cobb & Co coach leading a cavalcade of more than 300 people travelling on horseback, buggies, wagons and bullocks.