Allan Cunningham spotted a possible dray route through the range in June 1827, but the pass was promptly lost. The explorer himself, returning the next year, mistook the better-known Cunningham's Gap for the one he had first seen and never reconciled the two. It took until April 1847 for the stockman Henry Alphen to rediscover the real pass, tucked between Mount Mitchell and Spicers Peak, the peak Cunningham had named for a convict superintendent who stumbled on it while chasing escapees from Moreton Bay. The reason the squatters cared was simple arithmetic. Without a route to the coast, Darling Downs wool faced an 800-kilometre haul to Maitland. Spicers Gap could cut that to a fraction, and Patrick Leslie and Fred Bracker put up their own money to clear it. Within weeks two drays had reached Ipswich, three days and a hundred kilometres faster than before.

A cleared track was not a road, and the early corduroy surfaces collapsed into the springs they were meant to bridge. The real work came between 1860 and 1865, soon after Queensland split from New South Wales, when the road became one of the young colony's first major public works. Surveyor Robert Austin directed the construction, with clerk of works Henry Clinton driving a gang of up to ninety labourers. They built it to last. Steep pitches were paved with stone pitching, large blocks set by hand and chocked tight with smaller stones; gentler stretches got macadamised broken-stone surfacing. Austin obsessed over drainage, cutting metre-deep drains along both sides and benching the road into the hillside where the slope demanded it. To keep rain from gouging the surface, he laid diversionary banks called whoaboys, named, it is said, for the driver's shout to his horses as they approached.

For a brief stretch in the 1860s the new road hummed with traffic, drays grinding up and over the range, inns at Clumber and beside the pioneer cemetery catering to the teamsters. Austin's grades were gentle enough that horse teams could replace the lumbering bullocks. It did not last. When the railway reached Warwick from Brisbane by way of Toowoomba in 1871, the slow haulage of drays could not compete with iron and steam, and Spicers Gap Road was all but abandoned almost as soon as it was finished. One thread of life held on. From 1861 the route carried the first telegraph line between New South Wales and Queensland, the wire that opened direct communication between Brisbane and Sydney, and it kept that traffic for 112 years until the line finally fell silent in 1973.

What the railway abandoned, time mostly spared. Walk the heritage trail through the Main Range now and the 1860s reveal themselves in extraordinary detail: stretches of original stone pitching still in excellent condition, corduroy timbers surviving west of the bend known as Devil's Elbow, the remains of a whoaboy 868 metres along, pick and chisel marks bitten into the bedrock. Over a kilometre of road is still benched across the mountainside. Governor's Chair, a lookout perched on the edge, has drawn picnickers since the 1930s and draws them still. Heritage authorities call this the best remaining example of sophisticated nineteenth-century road engineering in Queensland, a working museum you can walk, where the labour of ninety men and the curses of a thousand bullock drivers are written into the stone.