1. On August 11, 1865, the first post office in the newly-established town of Phoenix, Arizona, was established. The town had just been incorporated earlier that year, and the post office was a crucial development in the growth of the town.

2. August 11, 1919, saw the opening of the Phoenix Indian School, a boarding school for Native American children. The school was controversial, as it aimed to assimilate Native American children into American culture, often through harsh methods such as forbidding them from speaking their native languages.

3. The famous western film star Tom Mix died in a car accident near Florence, Arizona, on August 11, 1940. Mix was known for performing his own stunts on film, and his death marked the end of an era in Hollywood.

4. On August 11, 1965, the Watts Rebellion began in Los Angeles, California. The uprising would last six days and lead to widespread violence and destruction. The unrest spread across the country, and many activists in Arizona were inspired by the events of the Watts Rebellion.

5. August 11, 2012, marked the opening of the Musical Instrument Museum in Phoenix, Arizona. The museum is home to an extensive collection of musical instruments from around the world, and visitors are able to listen to recordings and see performances using the various instruments.