The Role of the Nation's Ports in Maritime Trade & Transportation

The Marine Transportation System (MTS) consists of waterways, ports, terminals, and intermodal landside connections that allow the movement of people and goods to, from, and on the water.  As part of the MTS, the Nation’s ports provide critical connections between waterways, highways, pipelines, and railroads.
U.S.-International Freight Flows by Mode and Weight or Value 
Waterborne vessels are the leading transportation mode for U.S.-international trade in goods, moving 41 percent of U.S.-international trade value in 2021—almost $1.9 trillion and nearly 1.6 billion short tons (69 percent of the total weight). In the 1st half of 2022, vessels continued to transport the majority of U.S.-international freight, moving more than $1.1 trillion (43 percent), two-thirds of which was containerized. The following figure shows the total (all), containerized, or noncontainerized monthly U.S.-international freight value transported by vessel.
For every dollar of trade goods exported by vessel from the United States, nearly two dollars are imported by vessel to the United States. Most consumer goods imported into the United States are relatively high value, lightweight, and transported as containerized cargo. Containerized cargo is cargo that will fit into an intermodal shipping container; container vessels provide economies of scale and have been one of the primary focal points of port performance in recent years. Dry bulk (e.g., grains, coal) and liquid bulk (e.g., chemicals, petroleum, liquefied petroleum gas, liquefied natural gas) are relatively low value and heavy-weight, accounting for the majority of exported tonnage.[1]  
Top 25 U.S. Foreign Trade Freight Gateways by Value of Shipments
The Nation's maritime ports handle the lion’s share of U.S.-international trade and transportation. They are the bellwether of U.S. economic activity. Of the Nation's top 25 Customs ports, water accounts for more than half of the trade value at the following 11 ports:
  • Baltimore
  • Charleston
  • Houston
  • Los Angeles
  • New Orleans
  • Norfolk
  • Philadelphia
  • Port Arthur
  • San Francisco
  • Savannah
  • Seattle
Water accounts for almost all (more than 90 percent) of the trade value at 5 of these ports:
  • Houston
  • Charleston
  • Norfolk
  • Baltimore
  • Port Arthur
The following figure shows the top U.S.-international freight gateways, as defined by Customs ports, by trade value. [2]
Footnotes
[1] U.S. Department of Transportation, Bureau of Transportation Statistics based upon U.S. Department of Commerce, U.S. Census Bureau, Foreign Trade Division, USA Trade Online, available at U.S. International Trade Data - Foreign Trade - U.S. Census Bureau as of August 2022.
[2] U.S. Department of Transportation, Bureau of Transportation Statistics based upon U.S. Department of Commerce, U.S. Census Bureau, Foreign Trade Division, USA Trade Online, available at U.S. International Trade Data - Foreign Trade - U.S. Census Bureau as of August 2022.