Settled in the 1860s, The Gap was a farming community until the mid-1950s. A Methodist church was built on donated land on Waterworks Road in 1873, and nearly 40 years passed before a school was opened (1912). In 1920, soldier settlement farms were taken up, mainly for poultry, but they declined from 42 to eight holdings by 1931. Whilst close to the reservoir, there was no piped water, and farmers had to rely on Fish Creek (a tributary of the Enoggera) or cart water from a tank near the reservoir. Farming diversified into bananas, vegetables and dairying, and vegetable growing continued until the early 1970s. In 1949 the Post Office directory recorded five poultry farmers at The Gap, two dairy farmers, a jam maker, the Stirling granite quarry, and the church and a grocer in Waterworks Road.
Since the extension of the tram to Ashgrove in 1938 housing had grown along Waterworks Road and arrived at The Gap in the late 1950s. There was no State high school in the district, and a site was chosen for one at The Gap in 1960. The local primary school bore the brunt of the school-age population until the Payne Road school (1970) next to the high school and the St Peter Chanel primary school (1972) were opened. The western end of the suburb had the Hilder Road school (1979).
Waterworks Road crosses Enoggera Creek at Walton Bridge where there is the Walton Bridge Reserve with a walking trail. West of the bridge is The Gap Tavern and The Gap Village shopping centre where the supermarket and 22 shops plus professional offices are found. Further west are the high school and the Uniting (formerly Methodist), Anglican, Baptist and Presbyterian churches. The Catholic church and school are to the north, off Chaprowe Road. In November 2008 a severe storm saw a number of houses in the Gap lose their roofs.
In 2014 the Brisbane City Council approved the first two stages of the controversial 10-stage, 980 home residential development on Leavitt Road near Upper Kedron by Western Australian based developer Cedar Woods. The planned new suburb between Upper Kedron and The Gap was located on 227 ha of cattle scrub and bushland.
The Gap’s southern boundary is Mt Coot-tha Park and its northern Enoggera Military Camp and Upper Kedron. The suburb’s main east-west features are Enoggera Creek, after leaving Enoggera Reservoir, and Waterworks Road.