US citizens do not need a visa for tourist or business travel to this country, but a valid US Passport is required.
Any US citizen who wishes to travel to Portugal for any purpose other than tourism or business negotiations (e.g. work, study, adoption, immigration, or stays longer than stipulated in the entry requirements) should contact the embassy or nearest consulate directly.
Regarding The Schengen Area
Travelers to Europe on business or tourism purposes may receive a visa for a short stay of one to ninety days, valid for all of the Schengen area countries. A Schengen visa issued by an embassy or consulate allows the holder to travel freely to all of these countries.
If you wish to visit only one Schengen country, you must apply through the embassy or consulate of that particular country.
If you wish to visit several Schengen countries, you must apply for a visa through the embassy or consulate of the country which is your main destination.
If you wish to visit several countries but do not have a main destination, you should apply for a visa at the embassy or consulate of the country which is your first point of entry.
If you do not need a visa for the Schengen country which is your main destination or first point of entry, please note that you may require a visa for other Schengen countries you wish to visit. You should then apply through the embassy or consulate of the first country which does require a visa.