Final answer:
Assimilation is not a government reform made during the Progressive Era; it refers to the integration of different groups into the dominant culture and does not relate to the election reforms of initiative, referendum, or recall brought about during that period.
Step-by-step explanation:
The Progressive Era was characterized by multiple government reforms aimed at increasing citizen participation and reducing the influence of special interests in the electoral process. Among the reforms enacted were initiative, referendum, and recall. Initiative allowed voters to propose new legislation, referendum provided a mechanism for the public to approve or reject existing laws, and recall provided a way for voters to remove public officials from office before the end of their term.
Thus, the correct answer to the question, 'Which of the following is not a government reform made during the Progressive Era?' is Assimilation, as this term does not relate to the direct democracy reforms of that time but rather to a policy regarding the integration of indigenous peoples or immigrant groups into the dominant culture.