1. Transportation Research Board (TRB), Paying Our Way: Estimating Marginal Social Costs of Freight Transportation, Special Report 246 (Washington, DC: 1996); Federal Highway Administration, Addendum to the 1997 Federal Highway Cost Allocation Study Final Report (Washington, DC: May 2000).
2. National Surface Transportation Infrastructure Financing (NSTIF) Commission, Interim Report (Washington, DC: February 2008), p. 12.
3. Intermodal Association of North America, IANA Factsheet, at www.intermodal.org/statistics files/lntermod- al%20Fact%20Sheet.pdf.
4. American Trucking Associations, U.S. Freight Transportation Forecast to...2018 (Arlington, VA: 2007).
5. NSTIF Commission, op. cit. note 2, p. 8.
6. American Transportation Research Institute, "The Trucking Industry," at www.atri-online.org/index .php?option=com_content&view=article&id=65<emid=76.
7. Ibid.
8. Sources included American Association of State Highway and Transportation Officials, Transportation: In- vest in Our Future-Revenue Sources to Fund Transportation Needs (Washington, DC: revised September 2007); American Road & Transportation Builders Association (ARTBA), A New Vision & Mission for America's Federal Surface Transportation Program (Washington, DC: November 2007); National Cooperative Highway Research Program (NCHRP), "Future Financing Options to Meet Highway and Transit Needs," Project No. 20-24(49) (Washington, DC: TRB, September 2006).
9. TRB, Trucking Industry Research Committee, E-Circular, "Trucking 101."
10. U.S. Customs and Border Protection, Department of Homeland Security, "User Fee Decals and Transpon- ders," at www.customs.gov/xp/cgov/travel/pleasure_boats/user_fee/user_fee_decal.xml.
11. Federal Aviation Administration, "Airport and Airway Trust Fund," at www.faa.gov/airports_airtraffic/trust fund.
12. USLegal, "Ton Mile Tax Law & Legal Definition," at definitions.uslegal.com/t/ton-mile-tax.
13. "Oregon Again Requires Weight Receipts in Trucks," Motor Carrier News (Oregon Department of Transportation), September 2008.
14. According to a February 2008 report, the Harbor Maintenance Fee generated $1.4 billion in Fiscal Year 2007; Government Accountability Office (GAO), Federal User Fees: Substantive Reviews Needed to Align Port- Related Fees with the Programs They Support (Washington, DC: February 2008), p. 15.
15. NCHRP, op. cit. note 8, estimates that 5-10 percent of customs duties would generate average annual revenue of $1.9 billion at 5 percent, or $3.9 billion at 10 percent.
16. ARTBA, op. cit. note 8.
17. GAO, op. cit. note 14, p. 15.
18. USLegal, op. cit. note 12.
19. Cambridge Systematics, Task 8 Technical Memorandum, "Analysis of Freight User Fee Funding Sources" (draft) (Cambridge, MA).
20. Ibid.