Left: ‘An Irish Peasant Discovering the Potato Blight of their Store’, by Daniel MacDonald (1847) Right: ‘Migrant Mother’ by Dorthea Lange (c. 1936) has been called the ‘ultimate’ photograph of the Depression era. Lange wrote of the woman, whose name was Florence Owens Thompson: ‘She said that they had been living on frozen vegetables from the surrounding fields, and birds that the children killed’