During the past two decades, the concentration of maritime container vessel calls at U.S. ports has shifted as the volume of containerized cargo handled by the ports has changed. In 2007, there were nearly 20,000 containership calls at U.S. seaports, accounting for 31 percent of the total oceangoing vessel calls made by all vessel types at U.S. ports.10 The top five container ports handled over half (57 percent) of these container vessel calls and 63 percent of the container cargo capacity (table 4). Just 2 years before, in 2005, the top five ports handled 55 percent of the calls and 61 percent of the capacity.
Between 2002 and 2007, the number of vessel calls at U.S. container ports rose 16 percent, from about 17,100 to 19,800 calls. By contrast, total vessel calls grew by 13 percent, from 56,600 to 63,800 calls.
Measured by the average vessel size per call, U.S. maritime ports also handled larger container vessels than in the past. The average size (per call) of container vessels calling at U.S. ports was nearly 48,000 deadweight tons (dwt) in 2007 (table 4). This is a significant increase from 38,000 dwt in 2000. Increases in vessel calls and containership capacity affect port operation, port productivity, and infrastructure requirements needed to accommodate the mega post-Panamax vessels. They also affect environmental considerations and community-impact issues. (See Spotlight 3 on ports and environmental concerns.)