49 CFR 100

Not found in the current CFR. No part 100 exists under title 49 in the eCFR as of 2026-08-23. That means either the part was removed or renumbered, or the citation in the publication is wrong. Either way, verify before relying on it — this is exactly the kind of stale reference worth catching.

What happened to it — verified: Range-anchor citation. Cited as the start of the conventional range “49 CFR 100-185” (the hazardous materials regulations). The regulations are real and current (parts 171-185 exist); part 100 itself has never been used, so the range's anchor number resolves to nothing. Current home: 49 CFR 171-185 (Hazardous Materials Regulations).

Citation counts come from the publication text, not from a summary. A high count is frequency, not legal weight — open the pub and read the citation in context.