From a carrier's name to its fleet

curl "https://api.cardog.app/v2/carriers?q=bison%20transport&country=CA" \
  -H "x-api-key: $CARDOG_API_KEY" \
  -H "Cardog-Version: 2026-10-26"

A motor carrier is a company that runs trucks across a border or a state line. Each one holds a US DOT number, and that number is on every roadside inspection and every reportable crash its units are involved in. /v2/carriers is that register and the walk from it to the units on the road.

1. Find the carrier

GET /v2/carriers?q=… takes one of three things and says which it read:

• a name or part of one (bison transport), matched against legal and trade names, best match first; state and country narrow it;
• a DOT number (245330), which returns that one carrier;
• a 17-character VIN, which returns the carriers that unit was observed under, most recent first.

Costs 1 credit.

2. Read the carrier

GET /v2/carriers/{dotNumber} returns two blocks that never mix.

declared is what the carrier filed about itself on its latest registration: power units, drivers, annual mileage, whether it carries hazardous materials or passengers. It is self-reported, and filedOn says how old it is. Do not divide anything by declared.mileage without reading that date.

observed is what roadside inspectors and crash reports recorded under the DOT number: distinct units seen, inspections, crashes, first and last seen. Counts, never rates.

A DOT number the road record names but the register does not (a unit's operators can name one) still answers 200: legalName and every declared field are null, observed is the record. 404 is for a DOT number on neither.

The register also holds a street address, a phone number and an officer's name. None of those are served; the domicile is city, state and country.

Costs 5 credits.

3. Walk the fleet

GET /v2/carriers/{dotNumber}/vehicles lists every unit an inspector or a crash report put under the DOT number, most recently seen first, with the roles it was seen in, its dates and counts, and a link back to every carrier it ran under.

Page with cursor until nextCursor is null; limit goes up to 500. Each page costs 5 credits. vehicles.count is the whole fleet, all pages.

These are observed associations: the unit and the carrier were on one dated row. They are not a confirmed current fleet and not ownership. A unit that changed hands appears under both carriers, each with its own dates, which is the point.

4. Walk back from a unit

GET /v2/vin/{vin}/operators goes the other way: every carrier a unit was observed running under. There is one item per day an inspection or a crash report put a carrier on the unit, most recent first, so a truck inspected ten times under one carrier is ten items.

curl "https://api.cardog.app/v2/vin/3HSDZAPR3KN125464/operators?expand=detail" \
  -H "x-api-key: $CARDOG_API_KEY" \
  -H "Cardog-Version: 2026-10-26"

Without expand an item is id, observedAt, source and value. expand=detail adds the record that put the carrier on the unit (fmcsa.inspection or fmcsa.crash) and the carrier as it stands on the register. This covers the power unit; a trailer's carriers come from GET /v2/carriers?q={vin}.

Costs 3 credits when there is at least one item, 0 when there is none.

In the SDK

const found = await client.v2.carriers.search({ q: "bison transport", country: "CA" });
const dot = found.carriers.items[0].dotNumber;
const carrier = await client.v2.carriers.getByDot(dot);
for await (const unit of client.v2.carriers.allVehicles(dot)) {
  const { items } = await client.v2.vin.operators(unit.vin, { expand: ["detail"] });
}

Where the record stops

Coverage is the US federal roadside record: US DOT-regulated commercial vehicles, including the Canadian and Mexican carriers that cross the border. A carrier that only runs inside one province is not here. A unit never stopped at a scale house is not here. No events is not evidence of a clean fleet.