California did not start putting exit numbers on freeway exit signs until 2002, as part of a statewide project to update all freeway exit signs. Because of engineering considerations, most of the new signs will look like this one on Interstate 5 approaching San Joaquin county route J11.
This sign is for traffic going north. Motorists going the opposite direction approaching this exit see a different type of exit sign, with the exit sign on a separate panel mounted atop the main sign, as in most other states. That sign seems to be the exception that proves the rule, however.