US containerized imports funnel through a strikingly small number of gateways: ~85% via the top 10 ports, ~31-33% through LA/Long Beach alone, and roughly half of all intermodal rail trains through metro Chicago

Summary

US containerized import flows are highly concentrated at both ends of the supply chain. At the seaport level, the top 10 US container ports handle roughly 85% of all containerized import volume (Descartes Global Shipping Report, 2024), and just two adjacent ports — Los Angeles and Long Beach — account for roughly 31-33% of the entire national total by themselves. At the inland rail level, the concentration is just as stark in a different way: about half of all US intermodal trains (and roughly 46% of all intermodal freight units) pass through the single metro Chicago interchange, where all seven Class I railroads converge. In short: a handful of coastal gateways receive the great majority of containerized imports, and a single inland rail chokepoint touches close to half of everything that moves onward by intermodal rail.

Port-side concentration: the data

This corpus's own BTS Port Performance Freight Statistics table (transport.bts_port_teu) carries monthly TEU throughput for BTS's 9 tracked top gateway ports, January 2019 through October 2022 (the source dataset has not been updated since; confirmed live). This is the only table queried in this session. Summed over that window:

Among just these 9 gateway ports, LA+Long Beach alone account for 39% of the combined volume, the top 3 (LA/LB/NY-NJ) for 57%, and the top 5 for 75%. This denominator is only the top 9 ports BTS tracks, not the full universe of US ports — so it overstates LA/LB's share of the true national total, which is why the externally sourced 31-33% figure (below) is the one to use for "share of all US containerized imports."

Cross-checking against current published industry figures

Because the BTS series stopped updating after October 2022, current-era concentration figures come from industry trade-data publishers who track all US ports, not just the top 9-10. Descartes' 2024 Global Shipping Reports put the top 10 US ports' combined share of national container import volume at roughly 85% (85.5% in August 2024, 85.3% in September 2024) — down modestly from over 90% a year earlier as some volume shifted to secondary gateways (e.g. Gulf and Southeast ports) amid West Coast labor-contract uncertainty and Red Sea/Panama Canal disruptions. Port of Los Angeles and PMSA reporting for 2024-2025 puts the Los Angeles + Long Beach combined share at roughly 31-33% of all US containerized imports — LA alone handled about 17-21% depending on the year, with Long Beach adding another 13-15 points. Both figures triangulate consistently with the BTS-measured relative ordering above (LA and Long Beach are consistently the two largest gateways, followed by NY/NJ), even though the absolute share-of-national-total number has to come from the external, currently-updated sources since the BTS series itself does not cover the full port universe or the current period.

Rail-side concentration: the Chicago chokepoint

Once containers leave the ports, inland movement concentrates just as sharply at a single interchange. The Association of American Railroads and the Chicago Metropolitan Agency for Planning report that roughly 50% of all intermodal trains in the US pass through metropolitan Chicago, and about 46% of all intermodal freight units nationally touch Chicago at some point in their journey. More broadly, roughly one in four of ALL US freight trains (not just intermodal) passes through or near Chicago, which is where all seven Class I railroads interchange traffic between the western and eastern rail networks. These rail-hub figures are drawn entirely from AAR and CMAP publications, not computed from any warehouse table — no rail-corridor table was queried in this session.

Data provenance and limits

• Warehouse table used: transport.bts_port_teu (BTS Port Performance Freight Statistics Program, Socrata rd72-aq8r) — the only table actually queried for this report. Covers only the 9 ports BTS itself tracks as the top gateways, monthly Jan 2019-Oct 2022; the source has not published since and this corpus has confirmed that live. It is real historical government data, not a proxy, but it is not a current-era series and not a full census of all US ports.
• External figures (top-10 national import share, LA+LB national share, Chicago rail-hub shares) come from Descartes Global Shipping Reports, Port of Los Angeles / PMSA public statistics, and AAR/CMAP rail-hub publications — cited individually above and in Sources below — because no freely bulk-downloadable current-era government series covers full national port-volume totals (the industry-standard NRF/Hackett Global Port Tracker publishes only point press-release figures, not a downloadable time series; this gap is confirmed in this corpus's own defect register, D-109). None of these external figures were computed from a warehouse table.

Every query behind this report

3 warehouse calls ran in this session, in order. Each is reproducible against the same snapshot.

SELECT port_name, SUM(teu) AS total_teu FROM transport.bts_port_teu WHERE type = 'Loaded' OR type IS NULL GROUP BY port_name ORDER BY total_teu DESC

SELECT DISTINCT type FROM transport.bts_port_teu

SELECT port_name, SUM(teu) AS total_teu, MIN(report_date) AS min_d, MAX(report_date) AS max_d, COUNT(*) AS n FROM transport.bts_port_teu GROUP BY port_name ORDER BY total_teu DESC