Once I have my Waiver, can I go to the U.S. whenever I want?

With a U.S. Entry Waiver you may travel freely between borders so long as the Waiver is valid and you bring all other documents that you would normally need to cross the border. U.S. Entry Waivers expire and must be renewed if you wish to continue traveling to the U.S. The waiver must be carried along with your passport as part of your travel documents.