Traveling into the U.S.
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Traveling into the U.S. / Requesting Invitation Letters

Visitors entering the U.S. must posses a valid passport. If you do not have a passport or need to renew your passport,  search on the internet for passport information from your home country.  

Passports, regardless of the type, must be valid for six months past the expected stay in the United States. This is a requirement for all categories of passports - regular, diplomatic, and official - when the traveler is seeking to enter the United States for business or tourist purposes, for a maximum of 90 days.

Information about applying for a visa is here.

Visa Waiver Program
International travelers for business or pleasure who are citizens of one of the 38 countries that participate in the U.S.’s Visa Waiver Program (VWP) can get a visa waiver.

Electronic System for Travel Authorization (ESTA)
All prospective VWP travelers must obtain pre-travel authorization via U.S. Customs and Border Protection’s (CBP) ESTA system prior to boarding a plane or ship bound for the United States.

Citizens and nationals of VWP countries can apply for an ESTA on CBP’s website.  ESTA is used to determine eligibility to travel without a visa to the United States under the VWP. Travelers who do not receive an approved ESTA must apply for a visa at the nearest U.S. Embassy or Consulate prior to travel to the United States.  Although an approved ESTA is generally valid for a period of two years, travelers should check their ESTA status on CBP’s website prior to travel.


ESTA Fact Sheet


Here are some travel-visa-related links from the U.S. government that will help you in preparing for the application:

U.S. Customs and Border Protection

It is recommended that after gathering basic information, you contact the nearest U.S. Embassy/ Consulate to establish the application process, schedule an interview, and any other region specific requirements. Here is a link to websites of U.S. Embassies, Consulates, and Diplomatic Missions.


Important Information for Those Planning to Travel Under the Current U.S. Travel Ban--July 6, 2018
The countries include Chad, Iran, Libya, North Korea, Syria, Venezuela, Somalia and Yemen.


To Obtain an Invitation Letter

The association is not responsible for obtaining visas. However, in order to assist with the travel visa application process,  ACVP will provide, upon request, a letter of invitation to attend the meeting to authors of papers that have been accepted and to non-authors who have paid the conference registration fee. The invitation "letter" will normally be provided in the form of a pdf file via email.

If you wish to receive an invitation letter to help with your visa, then submit the information listed below to

Include the following in your invitation letter request:

Your full name (as it appears on your passport) - please use CAPITAL letters for Your family name (also called your last name or surname);

Your "pre-title" (Dr., Mr., Ms.);

Your job title (for example: BS/MS/PhD student, Research Associate, Assistant Professor, Director of ….., Research Scientist (companies/ government) etc.);

Your affiliation (university, company, organization etc.);

Postal address (this may be either your work or home address, whichever you prefer), make sure that you include room number (if required), building, street, city, state, postal code and country


Dr. William HOWELL
Scientific Research Program Manager
Natural Resources Canada
Mining and Mineral Sciences Laboratories
P.O. Box 57023 Station M
Calgary, Alberta T2P 3C1 CANADA

This information is required so that we can send you an electronic letter of invitation, but it does not give you a visa or guarantee that the U.S. embassy will grant a visa.

Submit your request for a visa invitation letter as soon as possible. Please allow 5 days for an email response.

Note that ACVP participants are responsible for conference registration, paying appropriate fees for conference activities, as well as assuming full responsibility for any travel and accommodation expenses, and their activities and arrangements while in the U.S.


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