1. On December 20, 1913, the Los Angeles Aqueduct was completed, bringing water from the Owens Valley to the city of Los Angeles. The project was controversial at the time, as it involved taking water from a rural area to supply the needs of a growing urban population.

2. In 1951, the first drive-in movie theater in California opened in West Los Angeles on December 20. The drive-in became a popular form of entertainment during the postwar era, allowing families to enjoy movies from the comfort of their cars.

3. On December 20, 1989, the Loma Prieta earthquake struck the San Francisco Bay Area, causing widespread damage and loss of life. The magnitude 6.9 quake resulted in 63 deaths and thousands of injuries, and caused an estimated $6 billion in property damage.

4. The California State Capitol building was dedicated on December 20, 1869. The building, located in Sacramento, is the seat of the state government and serves as the ceremonial center of California politics.

5. In 2019, California became the first state to mandate later start times for middle and high schools, beginning in the 2022-23 school year. The law, signed by Governor Gavin Newsom on December 20, aimed to address concerns that early school start times are harmful to adolescent health and well-being.