I want to tell you about an article on Sweden Abroad:http://www.swedenabroad.com/en-GB/Embassies/Washington/Services-for-Swedes/US-Visa-Information/
Information regarding visas and permanent residence cards (green cards) is available from U.S. authorities.
The Non-Immigrant Visa Unit at the U.S. Embassy in Stockholm can provide information on ESTA, and different categories of temporary visas (including work visas). You can contact them via email or phone.
The Immigrant Visa Unit at the U.S. Embassy in Stockholm provides services for those wishing to take up permanent residence ("green card status") in the United States.You can contact them via email or phone.
U.S. Citizenship and Immigration Services (USCIS) is the U.S. government agency that oversees immigration to the United States - both temporary and permanent.