Martin Luther King Jr. became so popular because he stood up to the government and many leaders and changed the system in non-violent ways. He used the ways that Mahatma Gandhi had used in India during the height of imperialism. Using these nonviolent ways, he was the key leader in leading the Civil Rights Movement.
He followed instructions but would stage boycotts. No one had ever gotten so far for the citizens in the country to change their ways. Many people in the United States knew who Martin Luther King Jr. was based upon his speeches and marches. He traveled to many places and during this time everyone had a television and could see what King was doing. Then he kept his popularity after he died.