Here are 5 facts in California history that happened on July 21st:

1. On July 21, 1878, the first telephone exchange in California was opened in San Francisco, allowing for the first long-distance calls in the state.

2. In 1965, on this same day, Bob Dylan controversially played an electric set at the Newport Folk Festival in Rhode Island. Although this event did not take place in California, it is worth mentioning because the state is renowned for its influential music scene and the event marked a significant moment in the history of folk music.

3. On July 21, 1947, the first commercial television station in California, KTLA, began broadcasting in Los Angeles, forever changing the way Californians consumed media.

4. California experienced one of its largest earthquakes in history on July 21, 1952, when a magnitude 7.5 hit Kern County, causing significant damage to buildings and infrastructure and tragically killing 12 people.

5. Finally, in honor of July 21st, California designated Avocado Day as a state holiday to celebrate the state's significant contribution to the worldwide production of avocados. The holiday recognizes the importance of the crop to the state's economy and cultural heritage.