If you are not from a country that participates in the Visa Waiver Program with the United States and you are presenting at ADASS XX, please email email@example.com as soon as possible if you require visa assistance. Include your mailing address, telephone number, and title of your talk or poster with your request. Note that the address cannot be a P.O. box since the letters are sent via FedEx.
If you are not presenting at this event, you may obtain a tourist visa (B-2) without an invitational letter from the organizing committee. Refer to the information on the U.S. Department of State Visitor Visas webpage.