If you transport cargo from the US into Canada, you need to learn about the eManifest program.
This program, implemented by The Canada Border Services Agency, requires electronic data about your cargo and the vehicles to CBSA before crossing the border. As of November 1, 2012 you will be required to use the eManifest program. Failure to do so will result in you being denied entry. Penalties may also be levied although penalties will be zero-rated (i.e. non-monetary) until May 1, 2013.