Monday marks the voter registration deadline for people wishing to cast ballots in the special election for City Council District 1, the Leeward Coast-Ewa seat vacated by Todd Apo last month.

Anyone who was registered to vote in the last election is automatically registered, but residents must re-register if they have changed their name, residence or mailing address.

The election is being held primarily by mail-in ballot, with walk-in voting at Kapolei Hale and Honolulu Hale from Dec. 13 to 17. Ballots must be received by the city clerk by 6 p.m. Dec. 29, when results will be announced.

Ballots will be mailed by Dec. 9.

Fourteen candidates are running in the special election.

Apo resigned Nov. 8 to take a job with Walt Disney Parks and Resorts in Hawaii.

An all-mail ballot with walk-in voting also was used for City Council special elections last year, to fill vacancies created by the deaths of Barbara Marshall in District 3 and Duke Bainum in District 5.

According to the City Clerk’s Office, those elections cost the city $225,000 for District 3, which was won by Ikaika Anderson; and about $170,000 for District 5, won by Ann Kobayashi.

City Clerk Bernice Mau has said District 1 has about 45,000 registered voters, about 2,000 fewer than District 5.

Apo won a five-person race for the seat in 2004 with 46 percent of the vote, and won re-election in 2008 against a single challenger, Garry P. Smith, with 67 percent.

CORRECTION: Celeste Lacuesta, a candidate in the Dec. 29 nonpartisan special election for City Council District 1 (Leeward Oahu), is a Democrat. She was identified as a Republican in a previous version of this story Saturday.