Adrian Florido

After anonymous threats targeting black students at the University of Missouri were posted online Tuesday evening, saying things like, "I'm going to shoot any black people tomorrow, so be ready," the fear on campus grew quickly.

Some black students were so scared that they left their dorms to stay with friends off campus. Others didn't go that far, but did stay inside and away from windows.

Presidential candidate Donald Trump's proposal to deport all 11 million immigrants living in the country illegally, along with their U.S.-born children, sounds far-fetched. But something similar happened before.

During the 1930s and into the 1940s, up to 2 million Mexicans and Mexican-Americans were deported or expelled from cities and towns across the U.S. and shipped to Mexico. According to some estimates, more than half of these people were U.S. citizens, born in the United States.

Republican presidential candidate Donald Trump repeatedly referred to "criminal aliens" and "illegal aliens" in the immigration plan he released on Sunday. "Alien," and especially "illegal alien," have become such staples in the vocabulary of conservative pundits and politicians that many immigrant rights advocates now reject those terms as derogatory and dehumanizing.

But it wasn't always like that.

The National Association for the Advancement of Colored People is holding its annual convention in Philadelphia this week. For much of its 106-year history, it has been the nation's preeminent voice for civil rights and social justice. Among the topics of discussion this week: recent events in Baltimore and Ferguson.

But NAACP leaders have also addressed claims that their organization is losing relevance, especially for young people who are coming of age in an era of online activism and new protest movements like Black Lives Matter.