On May 9, 2008, USCIS published a proposed rule that would increase the maximum allowable period of admission or extension of stay for Mexican and Canadian TN nonimmigrants from one year to three years. Under the proposal, TD dependents would also be eligible for the same admission or extension periods. Public comments on the proposal were due by June 9, 2008.
October 15, 2008 
USCIS published the final rule, making no changes to the proposed rule. The final rule is effective October 16, 2008.