The North American Transportation Statistics (NATS) Online Database contains data for Canada, Mexico, and the U.S. and is free to use. Along with being able to view data online, tables can also be downloaded in .xls and .csv formats.
From the Bureau of Transport Statistics:
New three-country data was added to the North American Transportation Statistics (NATS) Online Database in this week’s 10th annual website update. The database, a product of the North American Transportation Statistics Interchange, contains comparable transportation-related data available from the United States, Canada, and Mexico in a one-stop online resource.
The database covers the following subject areas: demographics, transportation, the economy, transportation safety, transportation’s impact on energy and the environment, domestic and international freight activity, domestic and international passenger travel, transportation infrastructure, and vehicles. The NATS Online Database is co-sponsored by the U.S. Department of Transportation’s Bureau of Transportation Statistics (BTS), the U.S. Census Bureau, and the federal-level transportation and statistical agencies of Canada and Mexico.
With text available in English, French, and Spanish, the NATS Online Database can be found at http://nats.sct.gob.mx/en/.