State names — abbreviate or not?

Which is correct? HP’s corporate headquarters are in Palo Alto, ______. a. CA b. California

Answer: a.

Explanation: To conform to AP style, abbreviate state names when used in conjunction with a town or city name. (However, if the city is not specified, spell out the full state name.)

David Davies published this handy AP style tipsheet.

Here’s a list of abbreviations for state and province names, including both current and old-style.