What is a U.S. Visa?

A citizen of a foreign country who seeks to enter the United States generally must first obtain a U.S. visa, which is placed in the traveler’s passport, a travel document issued by the traveler’s country of citizenship.

Certain international travelers may be eligible to travel to the United States without a visa if they meet the requirements for visa-free travel. The Visa section of this website is all about U.S. visas for foreign citizens to travel to the United States.

(Note: U.S. citizens don’t need a U.S. visa for travel, but when planning travel abroad may need a visa issued by the embassy of the country they wish to visit. In this situation, when planning travel abroad, learn about visa requirements by country, see country information in the International Travel Section section of this website.)

More Information about Visas

Invitation Letters (LOI)

Delegates from certain countries may require a Letter OF Introduction (LOI) in order to apply for a visa to enter USA.  This letter is used in the same way as an invitation letter when applying for a visa through a US embassy or consulate, or online through the US Embassy website ((,issue%20or%20deny%20the%20visa).

You must be registered to attend the conference in order to download the LOI.  The LOI can be downloaded by logging into the conference website’s registration area (shopping cart) and then scrolling down to the bottom of the page where the DOWNLOAD INVITATION LETTER button is located.

WPA is not responsible for issues related to visa obtainment.

If you have further questions, please contact