'Big Rock Candy Mountains' was first written and performed by Harry McClintock in 1928. The song tells the story of a wanderer traveling to a mythical hobo paradise and was based on several older folk songs McClintock learned from his days as a hobo.
Hobos were migrant workers, usually very poor, who would travel around America looking for any sort of job that they could get. They developed their own culture, including songs like this.
Painting is “Homeless Man, Study for 'Destination Unknown” by Maynard Dixon.