Transportation Safety Program Extension Act of 2003 - Makes specified Highway Trust Fund amounts available for the period of October 1, 2003, until February 29, 2004, for the Secretary of Transportation for administration of motor carrier safety programs, motor carrier safety research, and border enforcement activities. Provides funding for such period for: (1) the motor carrier safety assistance program (including for information systems); and (2) highway safety programs (including for highway safety research and development, occupant protection incentive grants, incentive grants for alcohol-impaired driving countermeasures, and the National Driver Register). Conditions the making of commercial motor vehicle and motor carrer safety grants to States from such amounts on a State's agreement that total State and local expenditures, exclusive of U.S. Government amounts, will be maintained at a level at least equal to the average level of those expenditures for the last two fiscal years before October 1, 2003.
Makes specified funds available for Coast Guard expenses for personnel and activities directly related to coordinating and carrying out the national recreational boating safety program. Prohibits the use of such funds available to the Secretary of Homeland Security for unauthorized purposes or to replace funding traditionally provided through general appropriations. Requires the Secretary to publish annually in the Federal Register a detailed accounting of the projects, programs, and activities funded.