The Montana Improvement Company began construction of a large lumber mill on the Blackfoot River in 1885. Construction continued into 1886, and the town of Bonner was built to house employees and managers. The mill had a rated capacity of 125,000 feet in eleven hours. In 1887, because of timber suits against the Montana Improvement Company, the Big Blackfoot Milling Company was organized; it absorbed the Blackfoot Milling and Manufacturing Company, incorporated in 1888, in 1891. Andrew Hammond, E. L. Bonner, Richard and Eddy and others organized the company and continued lumber operations. In 1898, Marcus Daly purchased the mill to provide mine timbers and lumber for his Butte and Anaconda mining and smelting operations. W. H. Hammond was the mill's first manager. He retired after the sale of the mill to Daly and was succeeded for brief periods by A. W. Griffin and James E. Totman.

Kenneth Ross had come to Montana from Nova Scotia via Pennsylvania to work on the Northern Pacific Railroad. He was later hired to build small lumber mills at Bearmouth, Montana, and owned a sawmill in Evaro, Montana, and supplied bridge timbers for the Montana Central Railroad; that business ended in 1892 because of competition from the timber empire of Daly, Hammond, and Clark. Those same men asked Ross to assume control of their lumber empire just after, promising that they would not mix politics with business. He served as manager of the Bonner operation until eighteen months later, when Daly involved him in politics. John R. Toole, one of Daly's confidantes, replaced him; Ross returned to the mill in 1900 as supervisor with Toole as the mill's president. During their management, they faced the Industrial Workers of the World (I.W.W.) and their agitation of the lumbermen who worked for the mill; both were threatened with death by I.W.W. operatives. Ross retired in 1925. He was succeeded by W.C. Lubrecht as general manager; he had worked at the mill since 1896, and served for over 40 years.

W.A. Clark interests constructed a dam at the confluence of the Big Blackfoot and Missoula (Clark Fork) Rivers in 1907 to supply power to Missoula and Bonner for lights and an electric railway. Those interests also established Milltown and a sawmill near the dam site. The Anaconda Copper Mining Company purchased that mill, retail yards in Missoula and Butte, and the entire holdings of Western Lumber Company and Clark interests in western Montana in 1928. The Milltown mill was operated in conjunction with the Bonner mill for some years until it was shut down.

The original Bonner mill burned in January of 1919 and was rebuilt in the summer of 1920. The Big Blackfoot Lumber Company was incorporated in 1909 and absorbed the Big Blackfoot Milling Company in 1910. The Anaconda Copper Mining Company purchased the Big Blackfoot Lumber Company that same year, making the mill the Anaconda Company, Lumber Department. In 1961, the mill changed its name to Anaconda Forest Products, a Division of the Anaconda Company. In 1972, Champion International Corporation purchased almost all of the assets of Anaconda Forest Products.

After all the timber directly around the mill was exhausted at the turn of the century, the logging operations were moved about fifteen miles up the Blackfoot River to Potomac. There were three logging camps established there, at Union Creek, Arkansas Creek, and Potomac proper. To provide efficient log transport, the company built the Big Blackfoot Milling Company Railway from the McNamara, Montana, landing to Greenough, Montana, about fourteen miles; the line was completed in 1904. The company used two Shay locomotives, flat cars, and a McGiffert log loader to load and transport logs south to the landing, where they were floated downstream to the Bonner mill. In 1910, construction began to extend the line north from Bonner to McNamara and the road was re-named the Big Blackfoot Railway. The Chicago, Milwaukee, St. Paul & Pacific Railroad, which completed its line through Missoula in 1909, acquired the Big Blackfoot and completed the line to McNamara in 1913, with complete acquisition in 1916.

The Potomac camp operated until 1916. From May to October of that year, the operation moved west to the Nine Mile Valley with headquarters at Stark, Montana. The Blackfoot valley was not logged extensively from 1916 to 1926. Operations resumed in that valley in 1926, when the mill's logging operations were moved to Greenough, Montana. The railway was extended the mail line fourteen miles to Sunset, then added branch lines up Belmont Creek, Blanchard Creek, and Elk Creek. That camp lasted until 1934, when operations moved to Woodworth, just south of Seely Lake, Montana, in the Swan Valley. It had both permanent and portable buildings, including bunk houses, a mess hall and kitchen, office and community building, school, library car, repair and machine shop, and family housing. The rail line extended another fourteen miles to Cottonwood, Montana. The ACM ran another line from Cottonwood to Woodworth and branch lines from Blanchard Flats to the Cottonwood Lakes to Monture Creek.

The headquarters was moved again to Salmon Lake in 1948 and Woodworth was abandoned. Log trucks largely replaced railway transport about the same time, and railway transport ceased completely by 1957. With the advent of trucks and portable logging equipment, the camps were no longer needed, and all the camps were dissolved in 1960. Twin Creeks became the new base for trucking and logging operations, with company offices and repair facilities there.

The retail department of the mill was the Interstate Lumber Company, which was established in 1911. It was headquartered in Missoula with retail operations throughout western Montana, including Butte, Deer Lodge, Hamilton, Helena, Stevensville, Twin Bridges, and Whitehall.

The Hotel Margaret was built in 1892 as a showhouse for Montana larch products and provided temporary housing for visiting managers and others.

John R. Toole and William Toole formed the Bitterroot Development Company in 1890 to supply timber to the ACM. Other Hamilton operations, part of ACM interests by 1892, included a mill, an electric plant, and the Ravalli Hotel, which was completed in 1896. There were close ties with Marcus Daly's home and other businesses near Hamilton, including copious land acquisitions.

The Hope Lumber Company was incorporated in Idaho in 1907 as a manufacturing subsidiary of the ACM. It had headquarters at Missoula and operated offices in Hope, Idaho. It logged extensively in Bonner and Kootenai counties in Idaho.

The Northwest Milling and Lumber Company was incorporated in 1900 with J. R. Toole as president. It sold its assets to the ACM in 1913.

The Bonner Lumber Company was incorporated in 1905 in Deer Lodge, Montana. The ACM purchased it in 1930.