The zoo says that pending the receipt of elephant-moving permits Toka, Thika and Iringa will travel to the PAWS Wildlife Sanctuary near Sacramento, Calif., after the Thanksgiving weekend.
It says the trio are undergoing training for their big move, and that areas around the elephant exhibit will at times be closed to visitors to help them concentrate.
The option of getting the animals to California by plane was taken off the table earlier this summer, and the latest plan has them rolling south on trucks in what is expected to be a 50-hour journey.
National zoo watchdog Zoocheck Canada has said at least two veterinarians and six handlers would be accompanying the elephants on their journey, with several stops for refuelling and checkups.
Toronto City Council voted in 2011 to send the three elephants to the U.S. facility after groups voiced concern about the animals' welfare.
Activists had previously said the zoo was in talks to borrow a Canadian Forces plane to transport the huge animals.