1. In 1790, the District of Columbia was established as the capital of the United States when Congress passed the Residence Act. It authorized President George Washington to select the site and plan the city, which would eventually be named after him.

2. In 1862, President Abraham Lincoln signed the Homestead Act, which offered free land in the western territories to people who would settle and develop it. The act helped to increase westward expansion and settlement, including in the newly created territories of Colorado, Dakota, and Nevada.

3. In 1918, the United States Postal Service issued a series of stamps commemorating the American Expeditionary Force's participation in World War I. The stamps featured portraits of General John J. Pershing, commander of the AEF, and other military leaders and emblematic of the war.

4. In 1954, the Supreme Court of the United States handed down its landmark decision in Brown v. Board of Education, striking down the principle of "separate but equal" in public schools. The decision paved the way for desegregation efforts and marked a significant milestone in the civil rights movement.

5. In 1987, the Metro rail system opened its first segment, connecting the Dupont Circle and Farragut West stations. The system has since expanded to include six lines and 91 stations, serving the District of Columbia and surrounding areas.