Traveling Abroad from the United States

When traveling abroad, scientists need to plan properly to ensure that they will be able to enter the country of their destination. Scientists in the United States—both U.S. citizens and non-citizens—need to plan ahead..

U.S. Citizens

U.S. citizens typically need a passport to enter a foreign country. Passports should be valid for six months beyond the scheduled visit.

Depending on the country of destination, U.S. citizens may need to obtain a visa. The U.S. Department of State provides U.S citizen entry/exit requirements for every country in the world. U.S. citizens can also contact Embassies and Consulates in the U.S. for their entry/exit requirements.
Country Specific Information from the Department of State
Foreign Embassies in the U.S.

Traveling to Canada
Everyone who enters Canada is required to provide proof of identification and citizenship. A passport satisfies these requirements, but U.S. citizens may also provide other specific forms of identification to meet these requirements. In most cases, if making a short trip to Canada, U.S. citizens do not need a visa.  
Requirements for U.S. Citizens Traveling to/from Canada
Who Can Enter Canada and Required Identification

U.S. Visitors and Residents

Foreign nationals must review their immigration documents before leaving the U.S. to make sure that they will be allowed to reenter the U.S.

Advance Parole
It is very important that foreign nationals who have applied for adjustment of their immigration status to U.S permanent resident remember that they may only travel abroad if they first obtain "advance parole" from the U.S. Citizenship and Immigration Services. Without advance parole, they will abandon their adjustment application and will not be readmitted to the U.S. 
Advanced Parole Tips from DHS
Advanced Parole from Customs and Border Protection

Visa Requirements
Travelers should determine well in advance whether they require a visa to enter their destination country. If a visa is required, contact the respective embassy for information on visa application.
Foreign Embassies in the U.S.

Academic Institutions
If your institution has an international office, the may offer additional guidance. For example, a student on an F-1 visa should consult the international office at his/her university.

Travel to Canada
Everyone who travels to Canada must provide proof of citizenship and identification. Travelers should also determine whether they will require a visa.
Who Requires a Visa to Enter Canada
From U.S. to Canada Visa Section (Canadian Embassy)