From A Grass Roots Tribute: The Story of Bonner Montana, 1976.

The prospect of work and a wide open country initially drew people to Bonner-Milltown.  Many others immigrated from Canada’s Quebec, New Brunswick, and Nova Scotia provinces, as well as Northern Maine.  Many others came from Scandinavia, especially Finland, via Michigan and Wisconsin.  They moved here because jobs in the mines and forests of the East and Midwest had dwindled or because working conditions there were intolerable.

In 1941, when the population of Milltown was less than 1,000, there were approximately 12 percent Finns, 15 percent, French Canadians, 20 percent, Swedes, 30 percent,  Norwegians, and 23 percent native-born and undetermined.  George Petaja, the first child born in Milltown, once recalled at least 20 different nationalities in the 1920s.
Finns
Conditions in Finland caused huge immigrations to the US between 1890 and 1910 as many farmers were forced off their land.  Finnish immigrants came straight from Finland to Bonner in considerable numbers, assured by relatives and friends that they could get work at the mill.
 
Because of the large Finnish population in the area, Riverside [Milltown] was first dubbed “Finn Town,” a name later given to Milltown Flat, or West Riverside, after Finn Hall was moved there.

Finns who came early worked at the Bonner Mill or building the railroads.  Some lived in cabins along the Blackfoot, but floods made them happy to take advantage of John McCormick’s leased lots in Riverside in the late 1800s.  They built homes with lumber from the mill, sometimes obtained by “midnight requisition,” apparently tolerated by the Company which was glad to have steady workers.  Single men stayed in boarding houses; there was at least one in Riverside in 1892.  They often worked in the logging camps in the winter, when the mill was closed.  By 1913, there were 570 Finns living in Milltown, about 2/3 of its population.

Finnish families came as well.  Concerned that the drinking and fighting of some single men gave a bad reputation to Finns in general, some families in 1895 formed a local chapter of the Finnish National Brothers Temperance Union, an organization with a distinct religious orientation. Within a few years it was taken over by a more left-leaning group of Finnish immigrants, and by 1904 the Temperance Society was dissolved, and their original hall was sold.

By 1906 a large number of men and women had joined the Socialist Federation, and a larger number, remaining non-members, had accepted the Socialist philosophy at least partially and were willing to follow its leadership.  In 1907, the more Socialist-leaning Finns built a new hall that had a stage and bench-seating for 150 people.  It was originally located near the current Bonner/I-90 exit, but in 1912 Clark offered to purchase a lot and move the building, to make room for his new mill.  The building was moved to its present location in West Riverside at the corner of Riverside and 4th Street in 1913.
 
There was great activity in Finn Hall, or the Sunomi Club as it was called, from 1913-18.  Dances were held regularly on Wednesday and Saturday nights.  A men’s athletic club was very active and a drama club utilized the stage located at one end of the building.  After WWI there was less activity in the Hall, and except for activity in 1939-40 when Russia and Finland were at war, the use of the hall died out.  The building was sold in the 1950s, and it is currently used for commercial storage. Long recognized for its white paint, the building is now brown.
 
When representatives (all Finns) of the Butte miners already on strike came to Bonner to find support in 1908, Finns in Bonner gave a very receptive ear to the issues of low wages and poor working conditions.  Workers of nationalities were represented in the walk out, but Finns were prominently in the leadership and comprised nearly two-thirds of the strikers.  Many residents remembered the Finnish women who jeered the non-strikers on their way to work.  In the end, the strike was unsuccessful; the mill hired a new group of immigrants.  However, Finns continued to be the dominant immigrant group in Milltown.
 
Labor strikes--brought about through the efforts of the Industrial Workers of the World (IWW)--broke out in 1917, led by Finns, again for better wages and the eight-hour work day.  Like before, the strike was unsuccessful, and many lost their jobs.  There was a second major exodus of Finns from Milltown but this time there were fewer immigrants who followed to take their place and the number of Finns declined.

Swedes also came to Bonner, drawn more by the railroads, though some certainly worked at the mill.  Many came via Minnesota and the lumber industry there.  For a time they established a small mission church on the east side of the Blackfoot River. Later it became part of Our Saviors Lutheran Church, one of the two churches in Bonner today.

Norwegians initially were a small percentage of the population (About 20 in 1906) but by the 1940s had increased substantially. The church, Our Savior’s Lutheran Church, was built in 1910 on land donated by the Anaconda Company.  The Lutheran Church was a definite contributing element to attracting a Norwegian settlement to Bonner.

French Canadians were among the earliest immigrants; they came first for the railroads and then the lumber mills and logging camps.  Andrew B. Hammond came from New Brunswick and recruited many of his fellow Canadians to work at the mill.  Most of the Canadians settled first in Frenchtown, west of Missoula, where there was an established Catholic church.  Later a mission church was established at Bonner and ultimately it split off on its own as the St. Ann’s Catholic Church, the second church in Bonner.

Japanese, Irish, and Italian immigrants were more associated with railroad construction--the Northern Pacific in the 1880s and the Milwaukee in 1908.  Their effect on Milltown’s settlement was only temporary; they did not stay.