Final answer:
The rise of social media has affected U.S. democracy by both enabling political participation and allowing misinformation, influenced social change through movements like MeToo and Black Lives Matter, and transformed how people consume political news and engage with politics.
Step-by-step explanation:
Three significant effects that the rise of social media has had on people in the United States include its impact on democracy, social change, and information dissemination. Social media platforms have become a double-edged sword in democratic processes, providing a space for open dialogue and participation but also for spreading misinformation and enabling extremist groups. On the positive side, for instance, movements such as MeToo and Black Lives Matter have utilized social media for broader mobilization and influence. Additionally, the technology has altered the landscape of news consumption, with a significant portion of Americans, especially among the younger demographics, turning to social media for political news, which has implications for both political engagement and the challenge of fake news.