Dayton is an unincorporated community and census-designated place in Lake County, Montana, United States. The population was 84 at the 2010 census. Dayton is located in northwestern Lake County at 47°51′54″N 114°16′37″W / 47.86500°N 114.27694°W, on the northwest shore of Flathead Lake, north of its Big Arm. U.S. Route 93 runs along the nor…Dayton is an unincorporated community and census-designated place in Lake County, Montana, United States. The population was 84 at the 2010 census. Dayton is located in northwestern Lake County at 47°51′54″N 114°16′37″W / 47.86500°N 114.27694°W, on the northwest shore of Flathead Lake, north of its Big Arm. U.S. Route 93 runs along the northern and western edges of the community, leading north 30 miles to Kalispell and south 22 miles to Polson, the Lake county seat.