Most student antiwar organizations were locally or campus-based, including chapters of the very loosely co-ordinated Students for a Democratic Society, because they were easier to organize and participate in than national groups. Common antiwar demonstrations for college students featured attempts to sever ties between the war machine and universities through burning draft cards, protesting universities furnishing grades to draft boards, and protesting military and Dow Chemical job fairs on campus. From 1969 to 1970, student protesters attacked 197 ROTC buildings on college campuses. Protests grew after the Kent State shootings, radicalizing more and more students. Although the media often portrayed the student antiwar movement as aggressive and widespread, only 10% of the 2500 colleges in the United States had violent protests throughout the Vietnam War years. By the early 1970s, most student protest movements died down due to President Nixon's de-escalation of the war, the economic downturn, and disillusionment with the powerlessness of the antiwar movement.