The student body at Kent State numbered about 20,000 and had been considered conservative, but not overly political. In fact they were thought of as rather passive politically. The shootings were a culmination of four days of demonstrations by members of the student body. The students were protesting the invasion of Cambodia by American forces.
In 1968 Richard Nixon was elected President. One of the promises he made was to end the Vietnam War. When the My Lai massacre was exposed in November of 1969 there was worldwide outrage and reduced public support for the war. Then a month later the first draft lottery was instituted since WWII. In April 1970, Nixon told the public he was going to withdraw large numbers of U.S. troops from Vietnam. So when he made his television address on April 30 to say we had invaded Cambodia the American people reacted strongly. In the speech Nixon addressed not only Cambodia but also the unrest on college campuses. Many young people, including college students, were concerned about the risk of being drafted, and the expansion of the war into another country appeared to increase that risk. Across the country protests on campuses became what Time magazine called "a nation-wide student strike."
The day after his Cambodia speech Nixon told a crowd at the Pentagon:"You see these bums, you know, blowing up campuses. Listen, the boys that are on the college campuses today are the luckiest people in the world, going to the greatest universities, and here they are burning up the books, storming around this issue."
This "bums" statement, was quoted over and over and helped to fuel the fires of dissent that were already getting out of control