1. In 1776, upon hearing the reading of the Declaration of Independence in Philadelphia, citizens of the District of Columbia took to the streets in celebration of the newly declared Independence Day.

2. In 1865, President Abraham Lincoln signed the District of Columbia Compensated Emancipation Act, which granted freedom to thousands of slaves living in the district and provided compensation to their former owners.

3. In 1919, the District of Columbia Police Department went on strike, leading to widespread looting and riots throughout the city. The National Guard was called in to restore order, and the strike was ultimately unsuccessful.

4. In 1945, President Harry Truman signed the United Nations Charter at a ceremony held at the White House in Washington, D.C. The signing marked the official establishment of the United Nations.

5. In 2009, the Metro system in the District of Columbia experienced a fatal crash that resulted in the deaths of nine passengers and the injury of dozens more. The incident prompted widespread safety inspections and reforms throughout the Metro system.