Final answer:
A major supporting detail from 'Ellis Island' is the fact that Ellis Island processed over 12 million immigrants from 1892 until its closure, reflecting its central role in US immigration history. The treatment of immigrants based on ticket class also represents an important theme of socio-economic divides.
Step-by-step explanation:
The question at hand necessitates the identification of a major supporting detail from the text "Ellis Island." A suitable supporting detail that outlines a key aspect of the immigrant experience at Ellis Island could be: In New York, Ellis Island opened up its doors to immigrants in 1892 and it processed over 12 million people in the 62 years it was open. This sentence encapsulates the extensive reach and significance of Ellis Island in the context of American immigration history. It provides a clear point of reference for understanding the volume of immigrants that passed through its doors, which serves as a major supporting detail by illustrating the pivotal role that Ellis Island played in welcoming new populations into the United States. Another notable detail is the differentiation in the treatment of immigrants based on their ticket class, illustrating the socio-economic divides and the federal government's stance on affluent immigrants as being less likely to become financial burdens.