U.S. Entry Requirements
According to the U.S. Department of State, all international visitors travelling to the United States need a passport.
Visitors from countries under the Visa Waiver Program (including the United Kingdom, France, Spain, Japan and Germany, amongst others) do not need a visa. Visitors from countries outside of the waiver program will need a nonimmigrant visa.
For more information on obtaining a visa, visit http://travel.state.gov/visa.