Note: Only include ports with a traffic of more than 250,000 TEU. MLW (mean low water): The average height of the low waters over a 19-year period.
Source: Adapted from US Department of Transportation, Port Performance Freight Statistics Program. & Port Authorities.
Note: Containership capacity refers to full ships. A port can accommodate larger ships if they are partially loaded or using the high tide navigation window.
Port locations and sites are preliminarily constrained by the maritime access they can provide. A core component of this access is related to the depth of the waterway system, the port access channels, and, more practically, the berth depth. The above map illustrates the channel depth of major container ports in North America as well as the potential containership capacity such a depth may accommodate. This does not necessarily mean that the port has the physical capacity to accommodate those ships since it could be lacking berth space, turning basins, equipment (cranes), or yard space to do so. The North American continent, unlike Europe and China, is not very prone to inland waterway distribution and is composed of three major maritime facades:
- The Eastern Seaboard, except for the St. Lawrence / Great Lakes system, offers no significant navigable river system, as the Appalachian Mountains are just a few hundred kilometers inland. The upper Great Lakes (Erie, Huron, Michigan, and Superior) offer good navigation depths, but navigation is limited by the waterways between the lakes and by winter ice. Further, access to the Atlantic is limited to the depth and lock size of the St. Lawrence Seaway, which is closed for a few months during the winter. The St. Lawrence allows deep-sea vessels to go deep inland, and maritime vessels can reach Montreal (draft of 37 feet and the capacity to accommodate ships up to 4,200 TEUs), which is at the same longitude as New York. Up to the mid-2010s, there were channel depth limitations for accessing several East Coast ports, with many of them limited to ships around the Panamax class (4,500 TEUs) except for Halifax (55 feet), Baltimore (50 feet), and Hampton Roads (50 feet) to enable these ports to accommodate Post-Panamax containerships. The expansion of the Panama Canal in 2016 provided an impetus to improve the nautical profile of many East Coast ports beyond the Panamax standard for which they were initially designed. New York and Charleston also reached draft depths of 50 feet and 52 feet, respectively, with substantial dredging investments. Savannah, a major container port, was able to extend its draft to 37 feet. Based on tidal conditions, it is possible for some Post-Panamax containerships in the range of 6,000 TEUs to call East Coast ports within a depth of 45 feet (Post Panamax I). However, the Eastern Seaboard also has a complex but underused coastal waterway transport system. The Intracoastal Waterway services most of the Eastern Seaboard and consists of a series of bays, inlets, sounds, and artificial canals.
- For the Gulf of America/Mexico, the Mississippi inland waterway system is extensive but limited to depths of less than 15 feet for the most part. Ports have a mean low water depth of fewer than 45 feet, limiting the containership capacity to less than 8,000 TEUs. The exception is Houston, which has undertaken massive channel widening and deepening, known as Project 11, to accommodate containerships above 8,000 TEUs. Ports along the Mississippi are predominantly handling barges loaded with agricultural commodities, which implies highly seasonal traffic (at the end of summer and fall). Additionally, the Mississippi system has a north-south orientation, while most commercial flows are east-west, suggesting limited potential to serve intermodal freight movements. For the Eastern Seaboard, the Intracoastal Waterway ranges from Texas to Florida.
- The Western Seaboard has four major deepwater gateways, Vancouver, Seattle / Tacoma (SeaTac Alliance), San Francisco / Oakland, and Los Angeles / Long Beach, but poor waterway access to the interior because of the Sierra Nevada and the Rockies. The only exception is the Columbia River basin, accessible to deep-sea ships up to Portland (draft of 42 feet), which is about 160 km inland. From Portland, container barge services go an additional 575 km inland. Most West Coast ports can accommodate ships of 12,000 TEUs or more. Prince Rupert is the container port with the deepest berth and can technically accommodate the largest containerships currently designed.
As the world’s container fleet upgrades to larger ships, major ports face the challenge of accommodating deeper vessel drafts. While a 39-foot channel could accommodate a typical Panamax container ship, post-Panamax I container ships handling above 5,000 TEUs require a berth depth of 42 feet or more. A depth of 50 feet is required to handle ships above 10,000 TEUs. Under such circumstances, many ports were inaccessible to the new post-Panamax container ships. The expansion of the Panama Canal to a depth of 50 feet and a capacity of 12,500 TEU (with its associated Neo-Panamax ships class) has also placed additional pressure. This has triggered a “race to the bottom” in dredging at several East Coast ports, including Miami (50 feet achieved in 2014), New York (50 feet achieved in 2016), Charleston (52 feet in 2022), Savannah (47 feet in 2022), and Houston (46.5 feet in 2025). Other ports have dredging plans. Yet, such projects are costly and require careful consideration of the marginal benefits they convey.