An Inter-American Driving License is an International Driver License that is issued in accordance with the provisions of the Convention on the Regulation of Inter-American Automotive Traffic signed at Washington, D.S., USA, in 1943. It allows any person to drive a motor vehicle in North and South American countries when accompanied by a valid National Driver Permit.
In December 1943, the Governments of the American Republics, Mexico, and other North and South American countries desirous of establishing uniform rules among themselves to control and regulate international automotive traffic on their highways, and to facilitate the movement of motor vehicles among States, have decided to conclude the Convention in order to effectuate the foregoing purposes, and have signed the Convention on the Regulation of Inter-American Automotive Traffic.
Under the Convention on the Regulation of Inter-American Automotive Traffic, every motor vehicle operator before admission to international traffic has to have such driving license as may be required by the laws of his State and a special international driving permit, the Inter-American Driving License.
The Inter-American Driving License has to be in a form, of the size, and contain the information prescribed in Annex to the Convention on the Regulation of Inter-American Automotive Traffic. Namely, the size of the Inter-American Driving License when printed is 14.5×8.5 cm (5 3/4//  ×  3 3/8 //). All information about a driver and county is printed in the English language.
In accordance with the Convention on the Regulation of Inter-American Automotive Traffic, no driver is admitted to international travel who is less than 18 years of age.
The validity of the Inter-American Driving License is recognized by all officials having regulatory powers over automotive traffic in each of the 20 countries that have signed the Convention on the Regulation of Inter-American Automotive Traffic, with the exception of the country in which the Inter-American Driver License is issued. The Inter-American Driving License is valid for one year from date of issue.
Thus, the Inter-American Driving License is translation of the National Driving Permit that gives you possibility to drive in twenty North and South American countries without problems with police officialdom.

 Information for US residents and citizens