{
  "name": "U.S. Manufacturing Source-Mix Shift Since 2018",
  "slug": "us-manufacturing-source-shift",
  "version": "3.0.0",
  "url": "https://www.mfgcalcs.com/signals/source-shifts",
  "formula": "For each family, country share = customsValue / year's reported annual import total x 100; a missing annual total excludes the comparison. Base year is 2018 exactly; families without that year are excluded. China delta = latest share - base share, percentage points. Top source = highest reported share; 'flipped' = the #1 source changed; 'gainer' is the largest share increase among countries reported in both endpoints. The measures are descriptive and do not identify why sourcing changed.",
  "unit": "percent; deltas in percentage points.",
  "source": "U.S. International Trade Commission (USITC) DataWeb per-family, per-country, per-year customs-value boards.",
  "provenance": "Derived entirely from USITC DataWeb, a work of the U.S. government in the public domain. Redistributable.",
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "attribution": "MFG Calcs (mfgcalcs.com), compiled from USITC DataWeb open data",
  "caveats": [
    "Families or years without a named China row are excluded because absence from a truncated country board is unknown, not zero.",
    "Endpoint board-value coverage is reported per family. A false endpointBoardsComplete means the persisted rows are retained top sources, not the full source-country market.",
    "Gainer comparisons require the country to be reported in both the 2018 and latest boards.",
    "Customs value is the declared import value, not landed cost or quantity; a share shift can reflect price as well as volume.",
    "This comparison does not attribute a sourcing change to tariffs or any other cause."
  ],
  "eligibilityRequirements": [
    {
      "code": "tracked-family-data",
      "description": "The tracked tariff family must have persisted USITC source-country history."
    },
    {
      "code": "exact-2018-baseline-and-later-endpoint",
      "description": "Source-country history must include exact calendar year 2018 and at least one later year."
    },
    {
      "code": "positive-annual-totals",
      "description": "Both endpoints must have a finite, positive annual import customs-value total."
    },
    {
      "code": "usable-endpoint-source-boards",
      "description": "Both endpoint source boards must contain usable nonnegative country values that do not exceed the annual total."
    },
    {
      "code": "named-china-at-both-endpoints",
      "description": "China must be explicitly present at both endpoints; absence from a retained board is unknown, never zero."
    }
  ],
  "asOf": "2025"
}