Nation’s Extensive Marine Transportation System Fills Many Roles

The United States is the world’s largest maritime trading nation, accounting for 1 billion metric tons, or nearly 20 percent of the world’s oceanborne trade. Over 95 percent of the U.S. overseas trade tonnage is shipped by sea. Federal, state, and local governments and private sector organizations all participate in financing the marine transportation system. Federal Funding for the Commercial Marine Transportation System

During fiscal years 1999, 2000, and 2001, federal expenditures for the commercial marine transportation system averaged about $3.9 billion each year, most of which was provided from general revenues. Federal Funding for the Aviation and Highway Transportation Systems

During fiscal years 1999, 2000, and 2001, federal expenditures averaged $10 billion each year for the aviation system and $25 billion each year for the highway system. Unlike the funding approach used for the commercial marine transportation system, which relies heavily on general tax revenue, the aviation and highway transportation systems were primarily funded by collections from users of the systems that are accounted for in trust funds. Most of these customs duties were deposited into the U.S. Treasury’s general fund. During the three- year period, assessments on system users were the funding source for about 88 percent of the amount spent on the aviation system and over 99 percent of the amount spent on the highway system.
What GAO Found

As the world's leading trading nation, the United States depends on a vast marine transportation system. Ninety-five percent of overseas trade tonnage moves by water, and the cargo moving through the U.S. marine transportation system contributes hundreds of billions of dollars to the U.S. gross domestic product. As it does with the nation's highway and aviation systems, the federal government participates with hundreds of public and private entities in maintaining and improving the marine transportation system. During fiscal years 1999, 2000, and 2001, federal expenditures for the commercial marine transportation system averaged $3.9 billion per year. Funding for about 80 percent of these expenditures came from the U.S. Treasury's general fund. During this same period, federal agencies collected $1 billion each year from marine transportation system users. During the same three-year period, federal expenditures for aviation and highway transportation systems averaged $10 billion and $25 billion, respectively, each year. Unlike the funding approach for the marine transportation system, which relies extensively on tax revenue, the federal funding approach for aviation and highway relies almost exclusively on assessments on users of the transportation systems.