Short Sea Shipping Promotion Act of 2007 - Amends the Internal Revenue Code to exempt from the harbor maintenance tax cargo contained in intermodal cargo containers and loaded by crane on a vessel, or cargo loaded on a vessel by means of wheeled technology, that is: (1) loaded at a U.S. port and unloaded at another U.S. port or a port in Canada located in the Great Lakes Saint Lawrence Seaway System; or (2) loaded at a port in Canada located in the Great Lakes Saint Lawrence Seaway System and unloaded at a U.S. port.
Defines the "Great Lakes Saint Lawrence Seaway System" as the waterway between Duluth, Minnesota and Sept. Iles, Quebec, Canada, encompassing the five Great Lakes, their connecting channels, and the Saint Lawrence River.