The US Library of Congress is a superb source of historical photographs on all sorts of subjects. Some of the most remarkable images are from rural areas in the US in the 1920s and 1930s. All the Library of Congress images are in the public domain.
Here is a small collection of pictures of farm dogs from the US in the 1930s.
Here is an example. This looks like a robust, working style Rough Collie type of dog to me.
About transformational1
I have many interests and I have had a varied career. I am a semi-retired professional dog trainer, specialising in the use of positive reinforcement. I do some consultations, I run instructor workshops and I am setting up a Dogs and Psychotherapy Research Project. I have a law degree from Melbourne University (but have never practiced) and I am passionate about Human Rights. My first degree was in Sociology. I worked as a social researcher on issues such as low income housing, women's refuges and women in the workforce. I live in an inner suburb of Melbourne, Australia, and I have a German Shepherd called Chance.
Wagging School Dog Training 