Parliament has unanimously passed special legislation to make 18 March a public holiday in Canterbury.
The Canterbury Earthquake Commemmoration Day Bill passed on Thursday allows people from the region to attend a national memorial service to mark the devastating Christchurch earthquake on 22 February.
The death toll from the powerful quake stands at 166.
The memorial service at North Hagley Park at 12.45 pm will be attended by Prince William, representing the Queen.
Labour Minister Kate Wilkinson says the quake is the greatest tragedy ever to hit Canterbury and the service will not bring an end to the grieving.
But while the city is still in the recovery phase, she says, the service will provide an opportunity for people to mourn and commemorate those who lost their lives in the quake.
Labour Party deputy leader Annette King says it is appropriate to set aside a day for the people of Christchurch to mourn the staggering loss of life.