Ports

Ports are coastal points where ships can dock at natural or artificial harbors to load and unload passengers, crew, and cargo. Artificial harbors, typically built specifically for use as ports, are made through dredging or the construction of sea walls, jetties, or breakwaters. The ports of Houston, Texas, and Long Beach, California, are especially large American artificial harbors (Houston is the country's busiest port for foreign tonnage). Certain ports are deepwater ports, enough so to accommodate fully laden Panamax ships—the largest size of ship that can pass through the Panama Canal.

A port of call is a port used as an intermediate stop for a cargo ship, such as for refueling or unloading part of the cargo. For cruise ships, a port of call is the port where passengers disembark for their vacation. Fishing ports are ports used for landing commercial fishing vessels. Warm water ports exist where the water doesn't freeze in the winter, which are of particular importance in international trade as they're usable year-round. This is one reason why so many of the busiest American ports are in warmer climates. Ports that handle primarily or exclusively containerized cargo, a relatively recent innovation, are called container ports.

Typically, a port uses cargo cranes, grain elevators, ramps, and conveyor belt machinery to handle bulk cargo. Depending on the local industry and imports, there may be long conveyor belts for loading and unloading coal and ore, or special equipment for loading and unloading liquid cargo (including oil) from tankers. Because of their importance in cargo transportation, ports will include warehouses for storage and nearby ground transportation systems in order to transport cargo inland. For instance, most American seaports have a nearby railroad terminal. Major ports will usually be located in a city with an airport as well.

In the United States, as in much of the world, ports are a significant part of global business. The Port of South Louisiana, for instance, which handles the most volume of any American port, handles over 200 million tons of cargo a year. River ports, though they may be less busy than seaports, are still key in inland cargo transport: on Lake Superior, the Twin Ports of Duluth, Minnesota, and Superior, Wisconsin, are together the largest freshwater ports in the world, and handle some 50–60 million tons of cargo annually. Ports often have critical connections to businesses or industries that aren't always obvious: for example, most of the grain exports from the Midwest are shipped overseas from the Port of South Louisiana.