36 CFR 702.13 – Soliciting, vending, debt collection, and distribution of handbills
(a) The soliciting of alms and contributions, commercial soliciting and vending of all kinds, the display or distribution of commercial advertising, the offering or exposing of any article for sale, or the collecting of private debts on the grounds or within the buildings of the Library is prohibited. This rule does not apply to national or local drives for funds for welfare, health, or other purposes sponsored or approved by The Librarian of Congress, nor does it apply to authorized concessions, vending devices in approved areas, or as specifically approved by the Librarian or designee.
(b) Distribution of material such as pamphlets, handbills, and flyers is prohibited without prior approval.
(c) Peddlers and solicitors will not be permitted to enter Library buildings unless they have a specific appointment, and they will not be permitted to canvass Library buildings.