Consequently, is a US driver's license valid in Portugal?
U.S. Citizens are entitled to drive in Portugal with their U.S. issued driver's license for a period no to exceed 185 days, provided they are not legal residents. During that period, U.S. citizens may continue to drive with their driver's license.
Subsequently, question is, do you need an international drivers license to drive in Europe? International Driving Permits are Required* in the following countries for US Licensed Drivers: Austria, Bosnia-Herzegovina, Croatia, the Czech Republic, Germany, Greece, Hungary, Italy, Poland, Romania, Slovenia, Slovakia, and Spain. *IDP enforcement may vary based upon car rental supplier as well as renting country.
Also question is, does Belgium require an international driver's license?
Tourists and temporary visitors are allowed to drive in Belgium on a valid license from a U.S. state. An International Driver's License is not required but some car rental companies may require one.
Do you need a license to drive in other countries?
It is illegal to drive without a valid license and insurance in most countries. Many countries do not recognize a U.S. driver's license, but most accept an International Driving Permit (IDP). IDPs may not be valid the whole time you stay abroad and may only be valid with a U.S. or local license.