What are some reasons why Mexico lost control of California?

The discovery of gold in California in 1848 triggered a massive influx of American settlers into the region, overwhelming Mexican authorities.

2. Lack of military forces:

Mexico had few military forces in California, and those that were there were poorly trained and equipped. This made resisting the American invasion difficult.

3. Divided loyalties:

Some Californios (native-born Mexicans) were sympathetic to the American cause and supported the annexation of California by the United States.

4. American technological superiority:

The United States had more advanced weaponry, which gave its forces an advantage over the Mexican military.

5. Diplomatic failures:

Mexico failed to secure international support for its claim to California, and the United States was able to negotiate the Treaty of Guadalupe Hidalgo in 1848, which officially ceded California to the United States.