Section 338 on Canada: the five proclamations of 8 September 2026
St. Gallen Endowment for Prosperity Through Trade / Global Trade Alert, 9 September 2026

These are the source tables behind the post. The changes they describe are announced and not
yet in force.

Files
  coverage_by_state_action_2025.csv  Trade covered by the three Section 338 baskets, per basket and
                                 in total, in three states: `pre` (22 August 2026), `mod` (15
                                 September, scope swap and stacking) and `ban` (29 September, import
                                 bans). Values in $bn of 2025 US imports from Canada.
                                 Columns: codes_annex and codes_traded_2025 are the annex line count
                                 and the subset with recorded trade; in_scope_bn is trade on the
                                 annex lines before treatment; banned_bn is trade excluded from
                                 importation; tariffable_in_scope_bn is in_scope_bn less banned_bn;
                                 at_50_bn is trade paying the full 50%; at_50_on_top_of_s232_bn is
                                 the part of that paying 50% in addition to Section 232;
                                 aircraft_5_bn is trade on the civil-aircraft list, which pays 50%
                                 on the non-civil tenth and so about 5%; carved_or_partial_bn is
                                 trade the Section 232 carve-out sheltered; usmca_share_pct is the
                                 share of in-scope trade entered under the US-Mexico-Canada
                                 Agreement; share_of_canada_imports_pct and
                                 banned_share_of_canada_imports_pct are shares of the $383.1 bn the
                                 United States imported from Canada in 2025.
  engine_twa_by_state.csv        Trade-weighted average applied US tariff by state, on 2024 import
                                 weights. canada_twa_tariffable_pct weights by trade that can still
                                 be imported and is the figure to quote;
                                 canada_twa_all_weight_pct is the same average before banned lines
                                 leave the base; canada_banned_2024_bn is banned trade on 2024
                                 weights; overall_twa_tariffable_pct is the average on all US
                                 imports.
  banned_lines_29sep_2025.csv    The 64 eight-digit lines excluded from importation from 29
                                 September, with 2025 import value, the banned share of the line,
                                 the rate on any remainder, the basket and the treatment tier.
  ban_certainty_2025.csv         Per annex entry, how much of the banned value rests on the
                                 packaging assumption. certain_2025_usd is banned on the face of the
                                 annex; small_container_2025_usd and cans_2025_usd are marked
                                 entries the tariff schedule itself puts in containers of four
                                 litres or less or in aluminium cans; silent_2025_usd is marked with
                                 no container information; bulk_2025_usd is marked on lines whose
                                 schedule text points to bulk containers.
  joiners_15sep_2025.csv         The 110 lines added to a basket on 15 September, with 2025 import
                                 value, the retained share where a parent line is only partly
                                 re-listed, and whether the line sits on the civil-aircraft list.
  leavers_15sep_2025.csv         The five lines removed outright on 15 September.
  top5_by_action_29sep_2025.csv  The largest lines per basket from 29 September, in $m of 2025
                                 imports, with covered and banned value and the treatment tier.
  retained_share_windows.csv     The five parent lines deleted at eight digits and re-listed only
                                 for some ten-digit children, with the retained share of each in
                                 three windows.
  s338-code-map-aug-sep-2026.xlsx  Every annex line across the July and September actions. Sheet
                                 Actions holds one row per listing (744); sheet Treatment by code
                                 holds one row per eight-digit line (664) with its treatment on 14,
                                 15 and 29 September; sheet Read me holds the reconciliation counts.
  s338-canada-explainer-260908.pdf  The seven-page explainer with the full method, the parameter
                                 table and the limitations.

Two bases, never mixed. Averages run on the model's 2024 trade weights. Coverage and scope values
use observed 2025 customs values. Both come from US import data at the eight-digit level.

Treatments. A line in a basket pays the 50% Section 338 rate unless it is carved out by the
Section 232 list of US note 51(c), sits on the civil-aircraft list of note 51(d), or is excluded
from importation. From 15 September the carve-out survives only for the dairy basket, so alcohol
and motor-vehicle lines in the Section 232 categories pay 50% in addition to Section 232.
Qualifying for the US-Mexico-Canada Agreement gives no relief under note 51(a).

Banned trade carries no rate. It leaves both the numerator and the denominator of every average
and is reported beside it as a value. A zero in a banned line's rate column records that no duty is
assessed, not duty-free access.

The packaged share is an upper bound. Where an annex entry is marked as covering only product in
direct-to-consumption containers, the whole entry is treated as banned, because no trade series
records container type. ban_certainty_2025.csv is what brackets that assumption.

We report the value of trade each measure covers, never the duty on it. No file here carries a duty
column.

Source: Global Trade Alert; USITC 2024 and 2025 imports. globaltradealert.org
