Now protests at political conventions are cordoned off far from the convention sites fearing a repeat of the protests and demonstrations at the 1968 Democratic convention.
It's also why the military draft was eliminated specifically to get a compliant, all volunteer army of draft age men and women who were a significant part of those 1968 protests.
All governments propagandize and indoctrinate its people. In the US it starts with standing to recite the "Pledge of Allegiance" in our schools, the standing for the "Star Spangled Banner", saluting the flag, belief in our "supposed" free elections, extolling the military as our "heroes", the Navy a "force for good", military flyovers at professional athletic events, spotlighting service men and women in the stands eliciting a standing ovation, playing "America the Beautiful" during the 7th inning stretch.
It's all part of the indoctrination process.
When this past season professional quarterback Colin Kaepernick was ostracized refusing to stand for the national anthem before an NFL game he was condemned in the MSM as un-American, ungrateful and a traitor to his country. Though what he did was not illegal and protected under the Constitution.
Standing for and singing the national anthem is voluntary and not required. But long standing tradition has made it "appear" as required behavior.
It's hard to know whether Americans are the most propagandized people ever. We certainly are obedient and compliant people accepting illegal government intrusions and generally accepting the governments explanations (propaganda?) of all significant national and international incidents.
It's almost certain the government knows with a population generally compliant to its strictures it can and will do anything with impunity knowing it will not be held accountable for its actions.
That's why "official" Washington represents the most dangerous, rogue state entity in the world and seen by most people worldwide as the primary threat to peace in the world.
Yet to most Americans we're the beacon on the hill embracing freedom and democracy.
In America "official" lies have been taken on a whole new meaning, become the natural order of things; a dystopia in real time.
 John W. Whitehead, "Battlefield America: The War on the American People" and "A Government of Wolves: The Emerging American Police State"