The Electoral Commission changed the boundaries to allow for population changes and the Otago electorate is no more.
Voters registered in the Otago electorate have had their names moved to either the Waitaki electorate or the Clutha-Southland electorate.
The registrars for the Waitaki and Clutha-Southland electorates have launched a push to get people ready for the October election, with 41,308 enrolment packs going out to Clutha-Southland and 47,105 to Waitaki constituents.
The packs will tell people which electorate they are in and whether they are correctly enrolled.
"People who have not received their enrolment update pack by Thursday will need to enrol. This is particularly important for people who may have moved house or who have recently turned 18, or become newly eligible," registrar Sue Skelt said.
The Electoral Commission is required every five years to look at the way electorates are structured.
As was the case for the previous commission, all seven electorates from Rakaia south have declined in population relative to quota requirements.
According to the Elections New Zealand website, the commission had to make significant changes to the electorates to meet the quota requirement.
That meant a progressive northward movement of boundaries from Invercargill.
The commission found that the population south of the Rakaia River and west of the Southern Alps was sufficient to create six electorates that were on average slightly over the projected quotas.
The boundaries of the Invercargill electorate move both east and west along the southern coast.
Queenstown, Arrowtown and the Roxburgh ward residents in the Otago electorate have been moved into Clutha-Southland.
Enrolment details can be updated on line at www.elections.org.nz.
Enrolment forms are also available by free-texting your name to 3676, or calling ENROL NOW (0800 367656), or at any Post Shop.
