Travel and Immigration
This Center for Disease Control travel site gives travel health-related information by destination on vaccines, health threats, etc. There are resources for yellow fever vaccination clinics and private travel clinics. There are links to all the state health departments and guidelines for safe food and water and mosquito and tick protection.
U.S. Passports and International Travel
This site covers applying for a passport, a requirement for traveling out of the country. Other links include travel checklists and U.S.-issued travel alerts and warnings.
U.S. Department of State Smart Traveler Enrollment Program (STEP)
STEP is a free service for U.S. citizens to be registered with nearest U.S. Embassy or Consulate while traveling abroad. This allows the Embassy or Consulate to alert you about local safety issues while abroad and to facilitate communications in the case of an emergency.
Obtaining citizenship through naturalization
This page covers how to become a U.S. citizen, including through military service or marriage.