Two identifiers answer different questions
A USDOT number is the entity identifier used in FMCSA records. MC is a docket prefix associated with operating authority. They are not alternate spellings of the same number.
Use what appears on the document
If the document labels a number MC, keep that prefix in the search. If it says USDOT, use USDOT lookup. With an unlabeled number, obtain the type from the sender or compare official results rather than assuming it.
Keep both when they resolve
Once you find the intended company, record its legal name, USDOT and relevant docket. Read the status from the current source row. A historical document may identify the company correctly while carrying outdated details.
Official sources
Referenced for the definitions and source checks in this article. Check the official page for current instructions.
Start with an identifier.
Find the company, compare the facts and follow the source.
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