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TT-005 · Customs mirror — method

Grade: REPORTED — counted by US customs authorities. Not observed by us, not modelled.

What it measures

Monthly US goods trade with a partner country: exports, imports, balance, in US$ millions,

customs value, all transport modes (sea, air, land).

Source

https://www.census.gov/foreign-trade/balance/c{CTY}.html — the US Census Bureau's published

country balance tables. Schedule C country codes — CORRECTED 2026-08-06 (the original seeding mislabeled

five of eight codes; caught when the corridor pages forced verification against the official

Schedule C list): India 5330, China 5700, Vietnam 5520, Singapore 5590, Indonesia 5600,

Burma 5460, Pakistan 5350, Afghanistan 5310. The stored monthly figures were always keyed by

code and are unaffected; only the display names were wrong. The published series

tt005.india.us-imports (5330) was correctly labeled throughout.

No API key. The richer port-level endpoint (timeseries/intltrade/imports/porths, which carries

CNT_VAL_MO — containerized vessel value by US port × origin country) does require a key;

that is a later upgrade, not a dependency.

Cadence and revision

Monthly, roughly five weeks in arrears. Census revises prior months. The collector upserts on

(cty, month), so a re-run silently adopts revisions. Any published figure must therefore be

pinned to the date it was retrieved.

Coverage

1985-01 to present. 497 months for India.

What it can and cannot answer

• Can: did US imports from a country actually rise or fall, and when.
• Cannot: which US port, which commodity, which vessel, sea versus air. All modes are pooled.

Why this instrument exists

It shares no machinery with TT-002. TT-002 infers activity from vessel movements (AIS); this

counts customs declarations. When they disagree, at least one is wrong — and that disagreement

is more informative than either series alone.

Known limits

• Total goods, not containerised sea freight — so it will never match a port-call series exactly.
• Country totals, not corridor-specific.
• HTML table scrape, not a versioned API: a layout change breaks the parse loudly (row count

drops to zero and the run logs an error) rather than silently.

Verification against TT-002

See ~/trimtab/findings/F-001-portwatch-india.md. Through calendar 2024 the two instruments track

within ±10 index points. From 2025-03 they diverge by 27–58 points in the direction that cannot

be true, which is why TT-002's Indian series is currently marked unfit for publication.