What Does a Highway Sign with the Letters “HC” Mean?

The initials “HC” on a road sign indicate a route for cars carrying hazardous cargo. Similar signs indicating that hazardous cargo is prohibited have the “HC” ringed in red and crossed by a diagonal red bar.

State-to-state variations exist for hazardous cargo signs. Some states substitute a “HM,” which stands for hazardous materials, for a “HC.” The sign often has white square background with black square text.

When hazardous cargo is permitted, a green circle may be placed around the “HC” or “HM”. The typical sign designator for something that is forbidden is a red circle with a strike-out bar.

Misha Khatri
Misha Khatri is an emeritus professor in the University of Notre Dame's Department of Chemistry and Biochemistry. He graduated from Northern Illinois University with a BSc in Chemistry and Mathematics and a PhD in Physical Analytical Chemistry from the University of Utah.


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