July 18, 1947 – President Harry Truman signs an Executive Order formally determining the line of succession for the Presidency beyond that of Vice-President (i.e., Speaker of the House, Senate President, etc.) and includes how to handle cases of disability. This later becomes the basis of the 25th Amendment to the Constitution which is ratified in 1967.
July 20, 1969 – A global audience watched on television as Apollo 11 Astronaut Neil Armstrong took his first step onto the moon.
July 23, 1934 – Bank robber John Dillinger (Public Enemy #1) is shot and killed by FBI agents while leaving the Biograph Movie Theater in Chicago.
July 24, 1911 – American archeologist Hiram Bingham gets his first look at the ruins of Machu Picchu, the ancient Inca settlement in Peru that is now one of the world’s top tourist destinations.