San Diego founded:

California was created by the Spanish in 1769 when they established Mission San Diego de Alcalá and the Presidio of San Diego. The city was the first European settlement in California.. Then in 1821, Mexico became independent of Spain and named the land north of Tijuana (Mx) Alta Califorinia.

In 1836, the Alta California and Baja California merged however, in 1846 the USA annexed California from Mexico and San Diego along with the rest of California became the 31st state.