There are a number of reasons why conservatives came to power during this decade. They include:
The protests against the Vietnam War
The Civil Rights Movement and the race riots of the later 1960s.
The Great Society
The countercultureWhat all of these things did was to create a backlash against the changes that were going on in American culture. All of the things mentioned above made traditional-minded Americans feel that American society was changing too drastically. They felt that society was moving too far toward liberal ways. They felt that things like respect for authority and individual willingness to work hard were disappearing. This led to a backlash in which conservatism came to dominate the American political scene.