Cranbrook is a city in southeast British Columbia, Canada, located approximately 10 km southwest of the confluence of the Kootenay Ri…Cranbrook is a city in southeast British Columbia, Canada, located approximately 10 km southwest of the confluence of the Kootenay River and the St. Mary's River. It is the largest urban centre in the region known as the East Kootenay. As of 2021, Cranbrook's population is 20,499 with a census agglomeration population of 27,040. It is the location of the headquarters of the Regional District of East Kootenay and also the location of the regional headquarters of various provincial ministries and agencies, notably the Rocky Mountain Forest District.