Pub. L. 86-682, tit. 39, pt. V, ch. 81, sec. 5002
Registration of letters containing currency
§ 5002. Registration of letters containing currency The Postmaster General shall accept for registration without prepayment of registry fee— (1) letters containing fractional or other currency sent for redemption to the Department of the Treasury; (2) letters sent from the District of Columbia, by the Department of the Treasury containing new currency for currency redeemed when marked with the word “register” over the official signature of the sending officer.