work/residence permit allows movement through EU/EEA?

Hello,
I am an American citizen who is about to be legally employed with a Portuguese company. I will be moving to Portugal on a work/residence permit.
Please correct me if I am wrong, but the Portuguese work/residence permit only allows me to lawfully carry out work within Portugal, work and/or residing anywhere else in the EU/EEA would require that I apply for a new work visa. Correct?

Thank you and best regards.

Yes, you may travel within the Schengen Area for up to 90 days in each country, however, there may be a specific condition of residency in order to maintain the Portuguese resident and work permission.

Also, in some cases, depending on the country and on a case-by-case basis, it could be possible to apply for a resident permit and work permission for another country of the Schengen Area.

See Status of Non-EU Member Country nationals who are long-term residents
http://europa.eu/legislation_summaries/ ... 034_en.htm