In New York State, the limit is 5 Pounds without a license
39.12 Special provisions relating to black powder.
(a) General.
(1) The provisions of this section shall apply only in connection with the transportation, storage and sporting use of black powder in quantities of five pounds or less when such powder is used in antique firearms or weapons or replicas thereof.
(2) Persons shall use, store, buy, sell, possess, transport, receive or dispose of black powder only in accordance with the provisions of the Labor Law and of this Part (rule).
http://www.labor.state.ny.us/workerprotection/safetyhealth/sh39_12.shtm