Mississauga (/ˌmɪsɪˈsɔːɡə/ ⓘ MISS-ih-SAW-gə), historically known as Toronto Township, is a Canadian city in the province of Ontario, situated on the western shore of Lake Ontario in the Regional Municipality of Peel, adjoining the western border of Toronto. With a population of 717,961 as of 2021, Mississauga is the seventh-most populous municipality in Canada, third-most in Ontario, and second-most in the Greater Toronto Area (GTA) after Toronto itself. However, for the first time in its history, the city's population declined according to the 2021 census, from a 2016 population of 721,599 to 717,961, a 0.5 percent decrease.