1. On August 4, 1911, the Panama-Pacific International Exposition opened in San Francisco. The World Fair was held to celebrate the completion of the Panama Canal and to showcase San Francisco's recovery from the 1906 earthquake. The exposition featured more than 20 countries and 43 states, attracting over 18 million visitors.

2. In 1964, the Vietnam War escalated as the U.S. Congress passed the Gulf of Tonkin Resolution on August 4. The resolution granted President Lyndon B. Johnson broad authority to conduct military operations in Southeast Asia, leading to an increase in American military presence in Vietnam.

3. August 4, 1915, marked the birth of actress and singer Gloria Stuart in Santa Monica, California. Stuart was best known for her role in the 1997 film Titanic, which earned her an Academy Award nomination for Best Supporting Actress at the age of 87, making her the oldest person ever nominated in an acting category.

4. An important milestone in California's environmental history occurred on August 4, 1976, when the state implemented the California Coastal Act. The law established a comprehensive program for the protection and management of the state's coastal resources, including beaches, wetlands, and estuaries.

5. On August 4, 1892, a labor dispute at the Redondo Beach Hotel in Los Angeles County erupted into a violent confrontation known as the Redondo Beach riot. The incident occurred when striking workers clashed with hired strikebreakers and the local police, resulting in several injuries and one death. The riot served as a reminder of the tensions between labor and capital during the Gilded Age.