An anti-counterfeiting measure; a polymer strip is embedded in the currency paper and is visible when the note is held up to bright light. The thread glows red when exposed to ultraviolet light, and cannot be reproduced by photocopiers or scanners. 10 Serial Number - Identifying number on the face of a note. Used primarily to thwart counterfeiters, serial numbering also allows the Treasury Department to track production. 11 Series Date - Each note is dated the year its series was authorized or first issued. Unlike coins that bear the year they were minted, paper currency carries the series start date throughout its lifespan. To determine the year the note was printed, the Treasury officials' signatures on the face must be cross-referenced with their dates in office.

A security thread is a security feature of many bank notes to protect against counterfeiting, consisting of a thin ribbon which is threaded through the note's paper.