When and how did Mexico take over California?

Mexico and California were Spanish possessions, so Mexico didn't 'take over' California, it was part of Mexico when they won independence from Spain.

I reiterate -- California was already part of Mexico when Mexico won their independence. It's called a 'province.'

The Spanish settled California. California was part of New Spain. Then "New Spain" including California became independent from Spain (it became Mexico). Then, in 1848, California was severed from Mexico and became part of the U.S. See www.californiahistory.net or www.californiahistory.org, or I expect you could also find other web sites.

Well the mexicans jumped the border and took over everything... it is still in progress but the takeover is almost complete.

I thought we took over Mexico.

Didn't we take over Mexico???? If not then... porque hablamos en ingles y no en espanol???