The time vessels spend waiting in port is a major factor contributing to port performance. Vessel dwell times are the amount of time that vessels spend in port actively loading or unloading cargo, which in turn contributes to both port capacity and throughput performance. Shorter dwell times are usually desirable because vessel and marine terminal operating costs rise with dwell time.
At Nation’s ports, container vessels have been a primary focal point of port performance in recent years, especially since they handle most consumer goods imported into the United States. The Nation’s top 10 container ports handled relatively low numbers of monthly Twenty-foot equivalent unit (TEU) in the first half of 2020, dropping to a low point of 2.8 million TEU in March 2020. The ports rebounded in the latter half of 2020, continuing to grow throughout 2021 and into 2022. They continue to handle an unprecedented number of monthly TEU, recently reaching a peak of 4.7 million TEU in May 2022. The growing number of TEU handled appears to be contributing to delays as containerships wait to dock and vessel turn times are prolonged. 
At the top 25
U.S. container ports,  the average container vessel annual dwell time was
estimated at 32.0 hours in 2021 as shown in the following figure, which was up by
about 3.9 hours from 28.1 hours in 2020. Overall, as shown in the figure below,
dwell times for container vessels fluctuated monthly, with dwell times
increasing steadily throughout recent months. 
Average container vessel dwell times for individual ports are shown in the online Port Profiles.
 The top 25 container ports are based on 2020
port rankings provided by the U.S. Army Corps of Engineer, Waterborne Commerce
Statistics Center as of October 2022.
 U.S. Department of Transportation, Bureau of
Transportation Statistics, calculated using AIS data from the U.S. Coast
Guard’s Nationwide Automatic Identification System (NAIS) archive, processed by
U.S. Army Engineer Research and Development Center, Coastal and Hydraulics
Laboratory, through the AIS Analysis Package (AISAP) software package as of
October 2022. Numbers may not add to total due to independent rounding.