(a) Aircraft departing from the U.S. One copy of the air cargo manifest shall be used as a clearance certificate when endorsed by the port director to show that clearance is granted.
(b) Scheduled aircraft. If a scheduled aircraft clears at an airport which is not the airport at or nearest the place of final take-off from the U.S., two copies of the air cargo manifest shall be filed. One copy shall be used as a clearance certificate when endorsed by the director of the port where clearance is obtained, and the second copy shall be attached to the first for use at subsequent U.S. ports.
ACE rules page: Part 122 in plain English