Nestled along Highway 2A in central Alberta, Carstairs sits roughly 48 kilometres north of Calgary and about 241 kilometres south of Edmonton. The town falls entirely within Mountain View County, with the neighbouring communities of Didsbury and Crossfield being its closest towns. A commuter bus service operated by First Student Canada connects residents to Calgary, with passengers boarding at the Carstairs Curling Club.
The land around Carstairs has a long history of human activity. Long before European settlement, the area was crossed by a network of routes known as the Ancient Trail – also called the Old North Trail or the Wolf Track – which First Nations peoples used for travel, with notable rock formations along the Rosebud River serving as regular resting points. In 1883, Sam Scarlett established a Stopping House near one of those formations, and it became a well-used stop for freighters, the North-West Mounted Police, and stagecoach lines along the Calgary and Edmonton Trail. When the Calgary and Edmonton Railway was laid in 1890, the new townsite was positioned roughly 4 kilometres west of Scarlett’s location to avoid crossing the Rosebud River. The town takes its name from Carstairs, Scotland, and its first post office opened in 1900, followed by its first school district in 1901. Carstairs was officially recognised as a town on May 15, 1903, under the designation Carstairs, NWT, before becoming Carstairs, Alta in 1905 when Alberta achieved provincial status. By the 2021 Census, the town had grown to a population of 4,898 residents living in 1,837 private dwellings – a 20.1% increase from the 4,077 people recorded in 2016, which itself reflected an 18.4% rise from the 3,442 counted in 2011. The town covers a land area of 11.77 square kilometres, giving it a population density of approximately 416 people per square kilometre.