(Sarah of the Clue Crew reads from a printing press at the Bureau of Engraving and Printing in Washington, D.C.)  The color of the first ink used in printing $1 bills & the part of the sheet it goes on gives us this word that dates from 1862
[DOC] [TLE] Full text of "The story of our post office [electronic resource] : the ... [PAR] In 1860, 27,000 miles of railroad were used for carrying mails, at an annual .....