Mount Crosby, an outer suburb of Brisbane, is 22 km south-west of the city centre. The mount (182 metres) is about one km west of the junction of Lake Manchester and Mt Crosby Roads.

John Oxley ascended the mount in 1824 during his exploration of Brisbane and named it Belle Vue Mount. Numerous streams run down from the Mount Crosby elevation, entering the Brisbane River either side of Colleges Crossing where Mt Crosby Road bridges the river. The crossing was described by Alan Cunningham in 1824 as a Fall, actually an extensive bed of alluvial gravel reducing the river's depth to a few inches. Such a seasonal crossing place was a magnet for settlement, and the locality immediately north of it went by the name of Mount Crosby. A primary school and a post office were opened in 1881 and 1882.

The origin of the name is undecided, possibly from 'Crosbie' on the England-Scotland border or from a gold prospector, George Crosby.

By the mid-1880s Brisbane's urban growth was outstripping the water supplied from Enoggera and Gold Creeks, and the Water Board undertook a scheme to pump water from the Brisbane River to a reservoir a few kilometres upstream from Colleges Crossing for gravity supply to the metropolis. The Mount Crosby water scheme began operation in 1893. A more efficient concrete weir wall was added about ten years later and a sedimentation basin and filters were installed during 1917-19. There were workers' cottages and the chief engineer's residence (1891) to ensure a permanent on-site workforce.

A tramway was built from the Tivoli coal railway (Ipswich) to Mount Crosby in 1913 to help in constructing the water treatment works. After completion of the works the tramway conveyed coal to the pumping station. Acquired by the Brisbane City Council from the metropolitan Water and Sewerage Board, the tramway apparently ceased operation in the 1930s.

Postwar urbanisation led to the Camerons Hill reservoirs (1971) north-east of Mount Crosby together with additional water treatment works.

In the mid-1970s land subdivisions along the north side of the river east of Colleges Crossing began, and the new locality was named Karana (later Karana Downs). Reservations for open space along streams were made, including the Karana Downs golf course (renamed Brisbane International Golf Centre). School sites were shown on various editions of street directories, but education was confined to the Mt Crosby school on Mt Crosby Road. Further north, around Camerons Creek, a second stage of subdivision began in the late 1990s, and this locality is the urban part of Mount Crosby. It also has linear parks along stream lines.

In 1998 Mount Crosby and Karana Downs were transferred from the Ipswich municipality to Brisbane City Council.

Mount Crosby's census populations were:

Census DatePopulation
1911129
1921243
1933373
1966301
20061260
20111728
Further Reading: 

Ray Rogan, One hundred years of service: Mount Crosby East Bank Water Works 1892-1992, Brisbane, Brisbane City Council, 1992

J.M. Powell, Plains of promise, rivers of plenty: water management and the development of Queensland, Published Brisbane, Boolarong, 1991

Karana Downs entry