[2] Formerly National Route 66, Queensland began to convert to the alphanumeric system much of Australia had adopted in the early-2000s and is now designated as A4.

Other towns situated along the highway include (from east to west): Gracemere, Kabra, Stanwell, Westwood, Gogango, Duaringa, Dingo, Bluff, Blackwater, Comet, Emerald, Bogantungan, Alpha and Jericho.

Running virtually east/west, the highway traverses the area known as the Central Highlands, and crosses the Great Dividing Range between Alpha and Jericho.

It is defined in four sections, as follows: The Northern Australia Roads Program announced in 2016 included the following project for the Capricorn Highway.

A lead project to upgrade the Mount Isa to Rockhampton corridor, including sections of the Capricorn and Landsborough Highways and surrounding state and council roads, at an estimated cost of $237.5 million, was in the planning and scoping stage.

[3][4] It runs from the Capricorn Highway in Comet to the northern boundary of Togara, where it becomes Comet–Rolleston Road, a distance of 22.5 kilometres (14.0 mi).

[3][5] It runs from the Capricorn Highway in Alpha to the Dawson Developmental Road in Windeyer, a distance of 121 kilometres (75 mi).