The Liberia tourist or business visa for U.S. citizen is usually valid for 1-year, multiple entries.
Economic Community of West African States (ECOWAS) citizens do not need a visa to Liberia:
Benin, Cote D'Ivoire, Gambia, Ghana, Guinea, Guinea-Bissau, Liberia, Mali, Niger, Nigeria, Senegal, Sierra Leone, Togo, Burkina Faso, and Cape Verde.
Note: The countries listed above may not be accurate, as countries periodically join and leave the ECOWAS agreement.
Citizens of all other coutntries not listed have the option of a single-entry visa within three months of the date of issue OR a multiple entry visa valid between 1-3 years from the date of issue.