started in the late 1980s on university campuses.
http://www.issues-views.com/index.php/sect/1001/article/1027# In 1988-89, at Tufts University, President Jean Mayer announced the establishment of "free-speech" and "non-free-speech" zones on campus. In protest, Tufts students from across the political spectrum united to overthrow the policy. To attract media attention, they partitioned the campus with tape and chalk to designate which parts of campus allowed free speech and which parts allowed only censored speech, making it look like Berlin in 1946. Embarrassed by the widespread media criticism that followed, Tufts abandoned the policy.
# At the Stillwater campus of Oklahoma State University (OSU), in 1998, a plan by some members of the student government to create limited "free speech zones" galvanized opposition from the University's faculty. Led by Professor Nancy Wilkinson, the Faculty Council emphatically condemned the idea, prompting President James E. Halligan to state publicly, "It's healthy for our students to question and interact with other ideologies." After this outcry, the student government never raised the issue.
# At the University of South Florida (USF) in Tampa, in the fall of 1999, the administration created two "speakers' areas" to which the exercise of free speech rights would be limited. Students and faculty immediately criticized this appalling restriction of their rights. Within weeks of its announcement, claiming that the policy was "too controversial," USF abandoned the plan.
Granted, the Bush administration has taken them to a whole new level.