International Travel Preparations
In addition to the passport requirement, each country has different entry/exit requirements. More information about a specific country may be obtained from the U.S. embassy or the consulate of that country. The information is also available from the U.S. Department of State website.
The State Department's Country Information page is helpful in understanding the subject country in regard to unusual immigration practices, health conditions, minor political disturbances, unusual currency and entry regulations, crime and security information, and drug penalties, as well as legal document requirements.