The Municipal District of Foothills No. 31 is a municipal district in southern Alberta, Canada adjacent to the south side of Calgary in Census Division No. 6. Despite sharing a common border with the City of Calgary of more than 15 kilometers and enveloping an agglomerate population of more than 60,000 people it has never been considered a part of the Calgary Census Metropolitan Area (CMA) by Statistics Canada. However, with membership in a regional metropolitan economic association, this Municipal District and its enclosed towns are generally accepted as constituent population, social and economic components of the Greater Calgary area.
In the 2011 Census, the Municipal District of Foothills No. 31 had a population of 21,258 living in 7,643 of its 8,401 total dwellings, a 7.7% change from its 2006 adjusted population of 19,731. With a land area of 3,642.9 km2 (1,406.5 sq mi), it had a population density of 5.8/km2 (15.1/sq mi) in 2011. Following High River’s 2012 annexation, Statistics Canada adjusted the M.D. of Foothills No. 31's 2011 population downward by 10 people to 21,248.