Ro/Ro Vessel Dwell Times
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.
In 2021, 7.5 million motor vehicles were imported to the United States, down slightly (4.8 percent) from 7.9 million in 2020. In October 2020, a peak number of motor vehicles were imported at about 868 thousand, up from the low of 202 thousand in May 2020. In 2021, the month-to-month number of motor vehicle imports was consistent, averaging about 625 thousand. 
As shown in the following figure, average Ro/Ro vessel dwell times at these top ports was estimated at 23.4 hours in 2021, up about 24 minutes from 23.0 hours in 2020. 
Average Ro/Ro vessel dwell times for individual ports are shown in the online Port Profiles.
 Based upon the following Harmonized Tariff Schedule (HTS) of the United States (2022) codes for motor vehicles: 870120, 870210, 870290, 870322, 870323, 870324, 870331, 870332, 870333, 870390, 870421, 870422, 870423, 870431, 870432, 870490, and 870600. U.S. Department of Transportation, Bureau of Transportation Statistics, analysis based upon trade data from the U.S. International Trade Commission, Data Web, available at https://dataweb.usitc.gov/ as of July 2022.
 The top ports are based on 2020 port rankings provided by the U.S. Army Corps of Engineer, Waterborne Commerce Statistics Center as of July 2022. Roll-on/Roll-off (Ro/Ro) vessels calls were only observed at 22 of the top U.S. ports. 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.