Mississauga occupies the southernmost portion of the region, and is, with 713,443 residents, the largest in population (the sixth largest in Canada). It reaches from Lake Ontario north to near Highway 407.In the centre is Brampton, a city of 523,911 (ranked 9th by population in Canada).t consists of three municipalities to the west and northwest of Toronto: the cities of Brampton and Mississauga, and the town of Caledon. The entire region is part of the Greater Toronto Area and the inner ring of Golden Horseshoe.