Hamilton is a city in and the county seat of Ravalli County, Montana, United States. The population was 3,705 at the 2000 census. Significant outlying population growth is shown in the area; the ZIP Code Tabulation Area for Hamilton's ZIP Code, 59840, had a population of 12,327 at the 2000 census.
Hamilton was founded by copper king Marcus Daly in the late 19th century. It was named for J.W. Hamilton, who provided the right-of-way to the railroad. Daly is said to have wanted to begin business in the then county seat of Grantsdale, but was denied the opportunity. He supposedly founded Hamilton out of his own pocket as a reaction to being rebuffed at Grantsdale.
In the summer of 2000, Hamilton made international headlines when forest fires throughout the Bitterroot Valley filled the area with smoke and prompted the evacuation of many residents. President Clinton declared a state of emergency in the area and dispatched National Guardsmen to assist with fighting the fires.