據我所知美國所有州都承認外國駕照。持外國駕照可以在美國境內短期駕駛。隻有某些州的租車公司policy要求外國駕照＋IDP。這些公司的policy可能against the law但訪客們隻是沒空跟他們玩。
所以外國駕照是必需品，而國際駕照隻是少數情況下的additional/optional。
加州的車管局官方網站寫得很清楚，加州不承認國際駕照，反而承認外國駕照。
https://www.dmv.ca.gov/portal/dmv/detail/dl/dl_info#international
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 person'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.
國際駕照隻有一部分國家承認，而美國不幸並不在列。所以IDP在美國是廢紙。
https://www.aaa.com/vacation/idpapplc.html
