Since April 30, 2013, visitors entering the United States by air or sea carrier no longer complete the paper I-94 or I-94W Arrival/Departure. Customs and Border Protection (CBP) officials at the Port of Entry gather travelers’ arrival/departure information automatically from their electronic travel records by scanning their passport. This generates an electronic arrival record with data elements found on the current paper Form I-94. The passport is stamped with the admission date, the class of admission, and the date that the traveler is admitted until.
On March 31 Chile joined the Visa Waiver Program (VWP). Qualified Chilean nationals traveling to the United States for business (B-1) or pleasure (B-2) will no longer require visas for travel if they meet all requirements for visa free travel. See http://london.usembassy.gov/niv/vwp.html.
Q. I traveled to the U.S. last year under the Visa Waiver Program with an ESTA, now I want to go again. Do I need a new ESTA? Do I need to update my travel details? How do I do that?
A. The ESTA registration is valid for 2 years, or until your passport expires, whichever is shorter. We recommend that travelers retain a record of the ESTA registration number, and check the validity of their ESTA before their new travel date.
You are not required to update your travel details each time you travel to the United States. However, if you wish to do so, you can visit https://esta.cbp.dhs.gov/esta/ and update your travel details there. You will need to have your passport number, registration number and date of birth to hand in order to retrieve your authorization.