From the article
A startling juxtaposition of migrant workers and a billboard advertising the American Dream which had gone so wrong for so many. As the men trudge towards San Francisco, carrying possibly everything they own, the poster exhorts them that next time they should really consider taking the train. A photograph taken ten minutes later would have, one hopes, have shown the billboard in flames. It is this sort of imagery though, that married with the written works of Steinbeck, Evans and Agee created the image of the USA during the Depression that we still associate with it today.