The Foundation for Individual Rights in Education (FIRE) has surveyed America’s colleges and found that 55 percent of them impose speech restrictions on students. See their website.
These colleges clearly and substantially restrict freedom of speech, purport to censor “offensive speech” (meaning, generally any antigovernment thought), or restrict “free speech” to a campus “zone.”
FIRE’s survey did not factor in private, religious schools, which expressly promote a religious view (as is their constitutional right).
FIRE has struggled and litigated against campus censorship for years, and has achieved some success. (When the organization started, 79 percent of colleges imposed censorship codes on students.)