The term “visa” refers to the visa stamp in your passport, not your I-20 or DS-2019 form. All non-immigrants (except Canadians) entering the US in F or J status are required to obtain the appropriate entry visa.
When you enter or re-enter the US, the visa stamp in your passport must reflect your current visa status (F or J) and must be unexpired. Also, if the visa has a limited number of entries, it must have a remaining valid entry available on the intended date of reentry to the US
If there are entries left on the visa, the visa should remain valid for re-entry until its date of expiration. However, students and scholars should consider the chance of unexpected need for a later re-entry, for example, due to weather delay.
If the visa stamp in your passport has expired and/or does not have a remaining valid entry available, and automatic revalidation of your visa is not possible, you must seek and obtain a new visa in order to re-enter the US
Canadian citizens generally are not required to possess a visa stamp to enter the US and may enter the US with valid I-20 or DS-2019 and proof of Canadian citizenship if entering by land or a passport if traveling by air as of 01/23/2007.
For non-immigrants with expired visas, trips to Canada or Mexico may not require a new visa application. This benefit is called “automatic revalidation of visa.” Currently, the automatic revalidation of visa benefit allows certain non-immigrants with expired visas to reenter the US after a 30-day or less visit to “contiguous territory.”
Contiguous territory is considered Canada, Mexico, or adjacent islands including Saint Pierre, Miquelon, the Dominican Republic, Haiti, Bermuda, the Bahamas, Barbados, Jamaica, the Windward and Leeward Islands, Trinidad, Martinique, and other British, French, and Netherlands territory or possessions in or bordering on the Caribbean Sea.
Citizens of Iraq, Iran, Syria, Libya, Sudan, North Korea, and Cuba are not eligible for the automatic revalidation benefit and would be required to have a valid visa for re-entry from contiguous territory.
Any non-immigrant who applies for a new US visa while traveling in “contiguous territory” is not eligible for automatic revalidation benefit. Thus if you apply for a visa in Canada and are denied, you are not allowed to re-enter the US under the automatic revalidation benefit.
To re-enter the US under the benefit of automatic revalidation of visa, you must:
If you need to obtain a new visa to re-enter the US, you should be prepared for a potentially lengthy wait and complex visa application procedures which sometimes require an in-person interview at a US Consulate abroad. Depending on your particular circumstances, you may decide not to travel and avoid the risk of a visa delay or a visa denial.
Students and scholars are recommended to apply for visas at the local US Consulate with jurisdiction over the home residence. Although it is possible for students and scholars to apply for visas at US Consulates in Canada, Mexico, and other countries worldwide, the risk of denial may be higher in these cases.
If a visa denial is received when a student/scholar applies in another country, the applicant is required to return directly to the home country to reapply at the local US Consulate. If denial or visa delay occurs, the applicant may not return to the US before receiving a new visa.
The most common reason for visa denial is “failure to demonstrate ties to the home country.” For more information, refer to the Non-Immigrant Intent section.
All F and J visa applicants must complete and submit Forms DS-156 (Nonimmigrant Visa Application) and DS-158 (Contact Information and Work History for Nonimmigrant Visa Applicant).
All male non-immigrant visa applicants between the ages of 16 and 45 - and others at discretion of consular official - must also complete and submit a DS-157 (Supplemental Nonimmigrant Visa Application).
All applicants for an F or J visa are required to demonstrate their intent to return to their home country following the completion of their academic programs. The burden is on the visa applicant to prove ties to the home country and establish “non-immigrant intent”. There are several ways you can be prepared to support your intent to return home in your visa interview:
You can read information from US Department of State about the requirement to demonstrate ties to your home country. In addition, you can find new, positive US Department of State guidance given to consular officials regarding interpretation of students' situations and “ties to home country”.
Refer to Ten Points To Remember When Applying For A Non-Immigrant Visa (from NAFSA, Association of International Educators)
During any visa application to the US, you may be subject to additional security and background clearances due to your citizenship or ties to specific countries, your field of study, or other reasons which are not publicly known. Delay in issuance of the visa may result as consular officers seek mandatory security advisory opinions from federal agencies on your background. Clearance may take several weeks to several months and no circumvention of the process is possible on grounds of US national security.
Citizens of certain countries may be subject to increased scrutiny and security clearances. Although the US Dept. of State has declined to release the list of countries on national security grounds, it is thought to include Afghanistan, Algeria, Bahrain, Bangladesh, Djibouti, Egypt, Eritrea, Indonesia, Iran, Iraq, Jordan, Kuwait, Lebanon, Libya, Malaysia, Morocco, Oman, Pakistan, Qatar, Saudi Arabia, Somalia, Sudan, Syria, Tunisia, the United Arab Emirates, and Yemen. Nationals or citizens of Cuba and North Korea are being subjected to increased scrutiny as well.
In addition, the US Department of State may be required to conduct a security clearance if you work in high technology, engineering, or the sciences. You should be prepared to be questioned closely about the details of your research. It may be helpful, if you are working in such fields, to have your department advisor or supervisor write a letter briefly detailing in laymen's terms, the nature of your work/research and, if applicable, noting that the technology is not for military use. This letter will not deter a security clearance, but it may expedite the clearance.
The US Department of State's list of sensitive technology fields requiring security clearance (called the Technology Alert List) is no longer public. You can get an idea of what may be on the list by using the Technology Alert List version from 2002. Use this as a guideline only.
You can also reference this outdated, but possibly relevant information published by the US Department of State regarding security check procedures.