I'm considering a trip back to the US and plan to rent a car.  I expect it would be best to have an International Driver's Permit on hand.  Where in Chiang Mai can you obtain an IDP?  Transportation office?  Elsewhere?

Thai drivers license is all you need.

I have visited the US and never been asked or required of an IDP. My 5 year DL has always been accepted no question asked for rental and proof. My last visit was last year rented from Enterprise and drove through Virginia. Pennsylvania  and New York. Have also rented from Herz and Avis no idp. I have done this on both cost.

 

I've always just used either a Japanese or Thai driver's license.  One year the pixie in me took over and I used my Japanese Alien Registration Card instead of my driver's license. No one seemed to notice.    Not too many American cops or rental agents read Japanese.

5 hours ago, connda said:

Where in Chiang Mai can you obtain an IDP?  Transportation office? 

If you want to be on the safe side you can obtain an IDP based on your Thai license at the "DLT" (Department of Land Transport alias "Transportation office").

There are couple of threads about this topic.

The IDP is only valid in conjunction with the original (Thai) license.

 

https://www.dlt.go.th/en/international-driving-licence/

Some years ago, a few U.S. states such as Florida passed laws requiring IDL for tourist from other nationsdriving in their states.  These laws were challenged by the U.S. Supreme Court and were found to be in violation of Federal law about 3 or 4 years ago.  Since then all valid foreign drivers licenses must be accepted valid for use in the USA for tourist as long as their drivers license from their native country has their name, date of birth, country the drivers license is from and DL number in English.  Thai drivers licenses meet this requirement. 

I would like to emphasize, this is for visitors for licensed in other countries.  If you start taking up residency in the USA, you must obtain a drivers license from the state you are living in within that states required time allowed.  In most states the time allowed to convert to a state DL is between 10 and 30 days.