1. In 1964, Martin Luther King Jr. addressed an audience in Washington D.C. during the third annual dinner of the National Conference on Religion and Race. His speech urged for a continued fight against racism and advocated for a time when all people, regardless of race or creed, would be treated as equals.

2. In 1979, the Three Mile Island nuclear power plant in Pennsylvania experienced a partial meltdown of one of its reactors, causing public concern over the safety of nuclear energy. In response, thousands of residents of the District of Columbia marched in protest against nuclear power.

3. In 1987, Marion Barry, the mayor of D.C. was arrested for drug possession after being videotaped smoking crack cocaine. He later served six months in prison and his political career never fully recovered.

4. In 2006, the D.C. government began recognizing same-sex marriages performed in other states, making it the first jurisdiction in the southern United States to do so.

5. In 2017, a group of protesters gathered at the Trump International Hotel in D.C. to demand that President Trump release his tax returns. The protest, held on Tax Day, was one of many such demonstrations held across the country.