Final answer:
The most significant impact of the Progressive parties was the improvement in the status of Native Americans.
Step-by-step explanation:
The most significant impact of the Progressive parties was the improvement in the status of Native Americans. During the Progressive Era, activists and reformers advocated for the preservation of Native American culture and the protection of their rights. This led to the passage of legislation such as the Indian Reorganization Act of 1934, which promoted self-governance and cultural preservation for Native American tribes. The Progressive parties played a crucial role in advocating for these changes and moving towards a more inclusive and fair society.
Learn more about Impact of Progressive parties on Native Americans.