At the 1968 Olympics in Mexico City, Tommie Smith and John Carlos -- who'd taken the gold and bronze medalists in the 200-meter dash -- took to the winners podium and raised their fists above their heads in a silent protest against discrimination against African-Americans in the United States. "If I win I am an American, not a black American. But if I did something bad then they would say 'a Negro.' We are black and we are proud of being black," Smith said of the protest.

Boxing legend Muhammad Ali famously refused to serve in the U.S. military during the Vietnam war, noting, “Why should they ask me to put on a uniform and go ten thousand miles from home and drop bombs and bullets on brown people in Vietnam while so-called Negro people in Louisville are treated like dogs?" In 2005, President George W. Bush awarded Ali the Presidential Medal of Freedom, calling him "a fierce fighter and a man of peace."

Following the Soviet invasion of Afghanistan, the United States led a boycott of the Summer Olympic Games in Moscow. The boycott would grow to 65 nations who refused to participate in the games.

Four years later, the USSR would return the favor, boycotting the 1984 Olympics in Los Angeles. "Chauvinistic sentiments and anti-Soviet hysteria are being whipped up in this country," the Soviet government said of the boycott, which 13 other communist countries would also join.

At the beginning of the 1995-1996 NBA season, Denver Nuggets point guard Mahmoud Abdul-Rauf decided that he wouldn't salute the American flag during the playing of the national anthem prior to games. The decision went unnoticed for some time; when NBA commissioner David Stern handed down a one-game suspension to the player. The NBA later reached a compromise, mandating that Abdul-Rauf stand for the anthem, but allowing him to close his eyes and face downward.

In 2014, following the death of Eric Garner after a confrontation with police in New York, Cleveland Cavaliers stars LeBron James and Kyrie Irving wore shirts emblazoned with the phrase "I Can't Breathe" -- Garner's reported last words -- while warming up for a game against the Brooklyn Nets. Nets players Jarrett Jack, Alan Anderson, Deron Williams and Kevin Garnett also donned the shirts.

In 2016, then-San Francisco 49ers quarterback Colin Kaepernick opted not to stand during the national anthem, saying, "I am not going to stand up to show pride in a flag for a country that oppresses black people and people of color ... To me, this is bigger than football and it would be selfish on my part to look the other way. There are bodies in the street and people getting paid leave and getting away with murder."