At Garrison Junction, the railroads from Butte and Helena meet and continue on the Missoula as one line. Also at Garrison, US Highway 12 from Helena and Interstate 90 from Butte merge on their way west to Missoula, making passing through Garrison the quickest way from Helena to Missoula. Garrison is not far from the Grant-Kohrs Ranch National Historic Site. The ranch displays the first century of development of the Northern Plains cattle industry, from the 1850s to the 1960s.
According to legend, a Yankee veteran from the Civil War settled in the valley and named the town after his hero, William Lloyd Garrison, a famous abolitionist.