Below is a picture of Cohagen. As you can see there isn't much there. If the "Cohagen Bar" (also pictured below) was once called Knudson's Tavern I wouldn't be surprised.
In the 1940 census, Emil Knudson, age 38, was listed as residing in Cohagen, Montana. His occupation was "bartender". It appears Emil was the head of his one-person household and an unmarried man at the time.
My Uncle Harold Knudson and his brother Emil owned (or were part owners)of the Cohagen Bar. They then moved to Miles City I believe the early to mid 40's and bought the Mint Bar. That went through a couple owners and that property is owned by the US Bank.
We live near Cohagen and found some high school papers in the attic of our bunk house belonging to a Donald J Knudson, or maybe it's Darroll Knudson, there are some art drawings signed J.D K. Also some from Custer County High School 1928 with the same name. D Matzen could these be a relative of your uncles? We would love to return these papers to a relative.
My uncle had a some other brothers. There were quite a few kids in the family. One was Steve and (I think it was Darold)I wonder if it was a relative that stayed with them. I do have some papers thet might give me some more information. I will look and see!