Från
http://www.dmv.ca.gov/dl/dl_info.htm#international om "internationellt körkort". (man behöver inte internationellt körkort i USA).
International Driving Permits
The State of California does not recognize an International Driving Permit (IDP) as a valid driver license. California does recognize a valid driver license that is issued by a foreign jurisdiction (country, state, territory) of which the license holder is a resident.
The IDP is only a translation of information contained on a personÂ’s foreign driver license and is not required to operate a motor vehicle in California. Citations issued to a person in California who has an IDP, but does not have a California driver license will be placed on the Department of Motor Vehicle database.
The IDP is also called an International Driver License, International License, etc.