What do you need to legally enter the United States?

According to U.S. Customs and Border Protection, a foreign national entering the United States must present a passport. That person may need a valid visa issued by a U.S. Consular Official, unless they are a citizen of Canada or a country that is a part of the Visa Waiver Program.

A list of the countries eligible for the Visa Waiver Program can be found at the U.S. Customs and Border Protection’s online info center, notes the official website. All foreign nationals must enter the country on an approved carrier (if entering by air or sea) and stay no longer than 90 days, unless approved for an extension, a long-term visa or residency.