1. Fernandez, L. Int. Environ. Agreements 10, 133–145 (2010).
2. Planas, R. Mexico and U.S. remove roadblocks for NAFTA trucking provisions. Americas Society/Council of the Americas News Analysis (8 July 2011); available via
http://go.nature.com/BFkmDm
3. Barla, P. Energy Efficiency 3, 123–131 (2010).
4. US Census Bureau International Trade Data (accessed 21 July 2011); available via
http://go.nature.com/DKjWrb
5. Southworth, F. Greenhouse Gas Emission Reductions from Freight Logistics (Pew Center on Climate Change, 2010).