The Central America-4 Free Mobility Agreement (CA-4;) is a treaty signed in June 2006 between the Central American nations of El Salvador, Guatemala, Honduras, and Nicaragua, establishing the free movement across borders between the four signatory states of their citizens without any restrictions or checks. Foreign nationals who enter one of the signatory countries can also travel to other signatory states by land (but not by air) without having to obtain additional permits or to undergo checks at border checkpoints. Similar to the Schengen Agreement in Europe, the CA-4 Agreement establishes a harmonized visa regime for nationals travelling to the area.[1]