1. In 1787, the United States Constitution was signed in Philadelphia. This historical event took place in Independence Hall, which still stands and is a popular tourist destination.

2. On August 18, 1877, the Grand Army of the Republic (GAR) held their national encampment in Reading, Pennsylvania. The GAR was a fraternal organization composed of veterans of the Union Army who served in the American Civil War.

3. Philadelphia Phillies legendary player Robin Roberts was born on August 18, 1926. Roberts was a Hall of Fame pitcher who played for the Phillies from 1948 to 1961, and later played for the Baltimore Orioles, Houston Astros, and Chicago Cubs.

4. On August 18, 1949, the first atomic-powered vessel, the USS Nautilus, was launched in Groton, Connecticut. The Nautilus was constructed at the Electric Boat Company in Pennsylvania, and made its first operational deployment in 1955.

5. The Gettysburg Battlefield Memorial Association was incorporated on August 18, 1864, with the goal of preserving the battlefield where the Battle of Gettysburg was fought. This association eventually became the Gettysburg National Military Park, which is visited by millions of people each year.