Port throughput can be measured from different perspectives. For
example, throughput could be measured by the amount of cargo or the number of
vessels that a port handles over time. Port throughput is affected by many
variables beyond physical capacity, such as:
the volume of
international or domestic cargo,
arrangements with shipping lines,
by extreme weather (e.g., hurricanes), and
inland origins and destinations.
Most coastal ports handle both domestic and international cargo
carried on oceangoing vessels, while inland ports (e.g., the ports of St.
Louis, Cincinnati, Huntington, Mid-America, and Pittsburgh) almost exclusively
handle domestic cargo moved on barges.
The throughput measures included in this program are summarized below. Vessel dwell times are captured monthly, the food and farm products
indices quarterly, and all other throughput measures annually in the Port
Profiles. Annual data may mask seasonal variations in cargo flows that
place periodic stress on available port capacity.