1. On August 18, 1846, the United States declared war on Mexico, which led to the annexation of California and other Southwest territories.

2. In 1868, the Transcontinental Railroad was completed on August 18, connecting California with the eastern United States and making travel and transportation much faster and more convenient.

3. On August 18, 1920, the 19th Amendment to the United States Constitution was ratified, granting women the right to vote in all states, including California.

4. In 1958, the first submarine cable connecting California and Hawaii was completed on August 18, providing a communication link between the two states.

5. On August 18, 1969, Jimi Hendrix performed his iconic rendition of "The Star-Spangled Banner" at the Woodstock music festival in upstate New York, which had a major impact on the counter-culture movement in California and around the world.