Truckinginfo -The value of freight moved between the U.S. and its North America neighbors increased 4.5 percent in 2014 compared to a year earlier, while over the longer term trucking has some lost market share to other transportation modes. The overall value of freight on all modes totaled $1.2 trillion.

http://www.truckinginfo.com/news/story/2015/03/u-s-freight-movements-with-canada-mexico-increase-4-5-last-year.aspx