Upvote:3
The Automobile Association(AA) in the UK publishes a list of countries where a UK licence holder requires an International Driving Permit.
I believe motoring organisations publish similar lists for their own countries but presumably because of the complexities involved in the requirement or non-requirement of an IDP between various specific countries there doesn't seem to be a definitive list for all drivers and all countries.
To further complicate matters different states of the USA have different requirements regarding IDPs.
People who drive in the U.S. must have a valid driver's license. Some states require an International Driving Permit (IDP) from foreign nationals, in addition to a valid license from your own country. Contact the motor vehicle department of each state you will drive in for its requirements.
Wikipedia shows the countries which recognise IDPs which of course is not the same as requirement.