Lakeside is an unincorporated area and census-designated place in Flathead County, Montana, United States. The population was 2,705 at the 2020 census, up from 2,669 in 2010.In 1892 the town was called Stoner, named after John J. Stoner, proprietor of a hotel near the shores of Flathead Lake. A community named Lakeside already existed in Roosevelt County. With its demise in 1920, this town changed its name. West Shore State Park is 5 miles south of town.