[5] Hamilton was founded by copper king Marcus Daly in the late 19th century.

[7] 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 Guard troops to assist with fighting the fires.

Hamilton is, as of 2004, home to two microbiological research and production facilities: the government-run Rocky Mountain Laboratories, and a branch of the Corixa Corporation (bought in the late 1990s from Ribi ImmunoChem Research, Inc.).

NIAID (National Institute of Allergy and Infectious Diseases) completed construction of a Biosafety Level 4 biohazard laboratory as part of the Rocky Mountain Laboratories (RML) facility in 2008.

This facility has begun operations using highly-pathogenic organisms including the Lentivirus family of viruses.

[14] However, plans to close the Kmart store were announced in January 2022, with its final day of business conducted on March 6, 2022.

[18] Being located in the dramatically scenic Bitterroot Valley Hamilton is a great place for outdoor activity.

[20] It is one of the skateparks built by Montana Pool Service, a project founded by Jeff Ament.

[22] Daly Hospital, part of Bitterroot Health, provides healthcare service in Hamilton.