The closest one I know of is in Los Angeles (There are others in San Francisco, and I believe - Oakland). Totally worth visiting if you get the chance, though....making a day trip out of Olvera Street(first street in Los Angeles - it's a walkthrough open market, Mexican food, vendors, etc.), Chinatown, Felipe's (awesome sandwich shop you may have seen on Food Network - my Dad took us there many, many times during my childhood), etc., is something I'm hoping to do again soon myself (my kids have never been). All these places, if I remember correctly, are within walking distance of each other. You may want to check them on Google Earth.
Good luck!