1. In 1901, President William McKinley was shot by Leon Czolgosz while attending the Pan-American Exposition in Buffalo, New York. Although the shooting did not occur in Washington, D.C., it had a profound effect on the city as Vice President Theodore Roosevelt was sworn in as the 26th President of the United States just six days later.

2. The Washington Monument was completed on September 6, 1884. The 555-foot marble obelisk had been under construction for over 30 years and was the tallest structure in the world at the time of its completion.

3. In 1968, over 1,000 protesters marched on the National Mall to protest the Vietnam War. The demonstration was part of a larger anti-war movement across the country and ended in clashes with police.

4. On September 6, 1909, the first international flight of a heavier-than-air aircraft took place in Fort Myer, Virginia, just outside of Washington, D.C. Orville Wright piloted the flight which lasted for 57 minutes and covered a distance of over 24 miles.

5. The Smithsonian Institution was established on September 6, 1846, with the signing of the Smithsonian Institution Act by President James K. Polk. The institution was founded with the goal of increasing and spreading knowledge through research, education, and public outreach, and has since become a world-renowned center for scientific research and education.