Final answer:
The derogatory term "White Trash" became widespread in literature and media during the Progressive Era in the United States, from 1890 to 1920.
Step-by-step explanation:
The term "White Trash" began circulating in newspapers and books prominently during the Progressive Era in the United States, which spans from 1890 to 1920. This period was marked by significant social and economic changes, including rapid industrialization, urbanization, and increased immigration, leading to widespread societal shifts and heightened racial and economic tensions. The proliferation of the derogatory term reflects the class and racial conflicts of the era, as well as the influence of media in shaping public opinion.