An act of Legislature established the National Port Authority in 1967 (amended in 1970) as a state-owned enterprise to manage, plan and develop all ports in Liberia. The Authority manages four ports, namely, the Freeport of Monrovia, the Port of Buchanan, the Port of Greenville and the Port of Harper.he largest port in the authority's network, Freeport of Monrovia was built by the United States military during World War II for strategic purposes. It handles most of the authority's imported cargo, some of which are transshipped to other Liberian ports and to third countries.