http://www.aircanada.com/en/news/130218.html

February 18, 2013

Effective immediately, when you travel to the U.S. from Canada or an international airport on Air Canada and you have a connecting flight at Toronto Pearson (YYZ), your bags will automatically be transferred to your connecting flight.

That means that you no longer need to collect your bags before proceeding to U.S. Customs and Border protection for processing and security screening, making connecting to the United States at Toronto Pearson (YYZ) faster, easier and more convenient than ever before.

Learn more about connecting through Toronto Pearson International Airport.
or watch the transfer videos showing how simple it is to connect if arriving on a flight from Canada or arriving on a flight from an International airport.

The same convenient transfer process is also available to Air Canada customers connecting at Montreal (YUL) and Vancouver (YVR).