I found this answer some time ago on another site:
I'm posting this for the benefit of anyone who comes across this thread in the future.
Under the 1943 and 1949 Inter-American Conventions on Road Traffic (variously referred to as "Inter-American Automotive Traffic Convention" and similar names), as well as several bilateral treaties between the United States and Mexico, *residents* (not to be confused with citizenship) of Mexico are permitted to drive their Mexican-plated vehicles in the US for up to 1 year. Their driver licenses issued by a Mexican state are valid in the US as long as they are valid by the issuing state - no time limit.
To sum up: valid driver license from Nuevo Leon (or any other Mexican state) allows a resident of Mexico to drive in the US. Valid plates from Nuevo Leon or any other Mexican state allow a resident of Mexico to drive in the US for up to one year. After that time period, the vehicle must return to Mexico.
This is a federal matter, so state/local laws are subordinate. A state may try to create or enforce a law preventing mexican-licensed drivers or vehicles, but the federal treaties prevent such laws from having legal force.
For reference see http://www.mass.gov/...manual/appendixA.pdf and you can lookup "Treaties in Force", hosted by the US Dept of State, search "Driving in Wisconsin with a Foreign License" etc. Again, the law is federal, so each state's guidance on the matter should be essentially the same.
From personal experience, law enforcement in areas away from the border may be suspicious at first of a License from Mexico. They may even tell you that you must get a License from _____ (name of the state where you got pulled over). However, some agencies can lookup the status of your foreign license and verify the validity. Know the law, it may be helpful to remember the name "1949 Inter-American Convention on Road Traffic". Print the pdf linked above and keep a copy in your car if you like.
Cheers
(This post was edited by Rolly on Mar 12, 2012, 1:48 PM)
Edit Log:
Post edited by Rolly
(Veteran) on Mar 12, 2012, 1:48 PM