1. On April 12, 1927, Los Angeles opened its first central library building to the public. The library was designed by architects Bertram Goodhue and Carlton M. Winslow, and it is now considered one of the most important historical landmarks in downtown Los Angeles.

2. In 1862, the California State Assembly passed the first State Professional Medical Act, which authorized the formation of the first state medical board in the United States. The board was responsible for regulating the practice of medicine in California and promoting public health.

3. Jazz pianist and composer Duke Ellington debuted his famous composition "Take the A Train" in Los Angeles on April 12, 1941. The song quickly became one of the most iconic pieces of American music and has been covered by countless artists over the years.

4. On April 12, 1981, the space shuttle Columbia launched from the Kennedy Space Center on its first mission. The shuttle spent five days in space before returning to Earth, marking the beginning of the era of reusable spacecraft.

5. The first California poppy reserve was established near Lancaster on April 12, 1976. The reserve provides a protected habitat for the state flower, the California poppy, and is a popular destination for wildflower enthusiasts and hikers.