1. In 1734, the Mission San Fernando Rey de España was founded in present-day Los Angeles County. It was the seventeenth Spanish mission in California and was established to convert members of the Tongva tribe to Christianity.

2. On October 20, 1822, California became a territory of Mexico after gaining independence from Spain. The territory included present-day California, Nevada, and parts of Arizona, Utah, and Wyoming.

3. In 1873, the University of Southern California was founded in Los Angeles. It began as a Methodist-affiliated institution focused on liberal arts and science education.

4. On October 20, 1944, the Greek passenger ship SS Kastellorizo was torpedoed by a German submarine off the coast of San Francisco. The ship sank in just six minutes, killing 31 people.

5. In 1989, the Loma Prieta earthquake struck the San Francisco Bay Area on October 17, causing significant damage and 63 fatalities. On October 20, the World Series between the San Francisco Giants and the Oakland Athletics began at Candlestick Park in San Francisco. The game was interrupted in the third inning when the earthquake struck, causing a 10-day delay in the series.