1. The Birth of the Golden Gate Park: On April 20, 1870, construction began on the Golden Gate Park in San Francisco. This park is one of the city's most popular destinations and is known for its beautiful landscape of gardens, lakes, and hiking trails.

2. Earthquake Devastation: On April 20, 1906, one of the worst natural disasters in the state's history occurred when a massive earthquake hit San Francisco. The quake, along with the subsequent fires, destroyed much of the city and claimed thousands of lives.

3. Hollywood Success: April 20, 1939, saw the premiere of the classic film "Gone with the Wind" in Hollywood. The movie went on to win ten Academy Awards and remains one of the most beloved films in history.

4. First Earth Day: On April 20, 1970, the first Earth Day was celebrated across the nation, sparking a wave of environmental activism that continues to this day. California has been a leader in environmental conservation, with organizations and policymakers acting as stewards of the state's natural resources.

5. Tragedy in Columbine: On April 20, 1999, the Columbine High School massacre took place in Colorado. Although not in California, this devastating event shook the nation and led to increased awareness of gun violence in schools.