Polson is a city in Lake County, Montana, United States, on the southern shore of Flathead Lake. It is also on the Flathead Indian Reservation. The population was 4,041 at the 2000 census. It is the county seat of Lake County. The city was named after pioneer rancher Stephen Daniel Polson. According to the United States Census Bureau, the city has a total area of 2.7 square miles (7.0 Square Kilometer), all of it land.