Most of Colombia's general cargo trade has been handled by four public ports: Barranquilla, Cartagena, and Santa Marta on the Atlantic coast and Buenaventura on the Pacific coast. These four ports were concessioned in 1993 to regional port "societies" established under company law. These societies are responsible for contracting with port operators for the use of facilities and supervising the facilities' use - they do not provide services directly. New laws abolished restrictive labor practices and have allowed stevedoring services to compete freely at each port. The liberalization of labor practices along with the privatization of port services has resulted in large and rapid improvements in productivity, lower fees for port users, and very attractive returns for the concessionaires. Productivity levels are higher than in most newly privatized ports in other Latin American countries - where in many cases the ports have been privatized with limited competition. The improvements have been realized with low initial investments, though recently the port societies have gone beyond investing in shoreside equipment and are starting to invest in infrastructure expansion.