With the most recent edition of the Federal Register, America’s Marine Highway Rule became final:

On October 9, 2008, the Department of Transportation published an interim final rule that established America’s Marine Highway Program, under which the Secretary will designate marine highway corridors and identify and support short sea transportation projects to expand domestic water transportation services as an alternative means of moving containerized and wheeled freight cargoes; mitigate the economic, environmental and energy costs of landside congestion; integrate the marine highway into the transportation planning process; and research improvements in efficiencies and environmental sustainability.
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This rule adopts the interim final rule, addresses Marine Highway Corridors (and continues to solicit recommendations for Marine Highway Corridor recommendations), and establishes eligibility requirements, criteria and information necessary to apply for designation as a Marine Highway Project by the Secretary of Transportation.

For more information, see FR Doc 2010-7899,  the MARAD press release, or the AASHTO journal.