Aruba Entry Requirements
Requirements for Entry Into Aruba as a Tourist

Western Hemisphere Travel Initiative Passport Requirements
Any U.S. citizen returning to the U.S. from Aruba via air is required to present a U.S. Passport boook.

The Western Hemisphere Travel Initiative requires all travelers to present a passport or other document that denotes identity and citizenship when entering the United States. Addtional information.

Other Relevant Information
The U.S. Customs and Border Protection has preclearance, for both immigration and customs at Reina Beatrix Airport. Upon departure from Aruba, U.S. bound passengers will be screened in Aruba prior to boarding any aircraft bound to the U.S.  A preclearance inspection is the same inspection an individual would experience at any U.S. airport of entry, the difference being it is conducted in Aruba. As a result, the traveler will not undergo U.S. Customs and Border Protection inspection again upon arrival in the U.S.. Upon arriving at a domestic U.S. airport, the traveler proceeds directly to a connecting U.S. domestic flight or departs the airport.

Addtional information- Aruba Traveler Article: Aruba: Arriving & Departing