The transnational corporation Clean Harbors handled over 40% of all shipments of waste imported into the US between 2007 and 2012 (mapped here). As the map shows, the sites where Clean Harbors imports waste into the US are not concentrated in one geographic region. Instead, they are located throughout the United States. Similarly, the places they export waste from in Canada are located across that entire country. If you click on an importer, you can see the facilities in Canada from which they import waste.