1. In 1790, Congress declared that the District of Columbia would be the capital of the United States, under the Residence Act. This decision was made in part because the city was located centrally between the two regions of the country, the North and the South.

2. In 1864, President Abraham Lincoln signed the District of Columbia Emancipation Act, which freed thousands of slaves in the city. This was a significant step towards the abolition of slavery in the United States, and it was a precursor to the Emancipation Proclamation, which would be issued the following year.

3. In 1955, the first edition of the Washington Post Sunday Magazine was published. This magazine quickly became a popular feature of the newspaper and featured articles on a wide range of topics, including politics, culture, and the arts.

4. In 1969, the Apollo 11 mission launched from Kennedy Space Center, headed for the moon. This mission included astronauts Neil Armstrong, Buzz Aldrin, and Michael Collins, and on July 20, Armstrong became the first human being to set foot on the moon.

5. In 1995, the U.S. House of Representatives voted to approve the creation of a National Women's History Museum in Washington, D.C. This museum, which would celebrate the achievements and contributions of women throughout history, has yet to be built, but efforts to establish it continue to this day.