Most Canadian citizens and many citizens from Visa Waiver Program countries can come to the United States (U.S.) without a visa if they meet certain requirements. The U.S. Department of Homeland Security website has helpful information for international visitors, including information on the Electronic System for Travel Authorization for those travelers who are eligible under the Visa Waiver Program.
You can also visit the U.S. State Department website to learn about requirements for nonimmigrant visas.
Letter of Invitation Requests
Some participants from outside the continental United States need to apply for a visa at the American embassy, consulate or the visa-issuing office in their country of origin.
To obtain a visa, you will need a letter of invitation. To request an invitation letter, please write to: ASSH Annual Meeting Information, 822 W. Washington Boulevard, Chicago, IL 60607. Or send your request by fax to (847) 384-1435 or by e-mail to email@example.com.