Last minute voter registration has been "very high" in the Dublin City area, according to officials.
Deirdre Ní Raghallaigh, senior executive officer with Dublin City Council, said it expects to add around 14,000 through the supplementary register for the five city constituencies.
This is twice the usual figure of between 5,000 and 8,000 for an election.
On the last day a total of 3,500 registered by post, in person or online - a figure Ms Ní Raghallaigh described as "very high".
More than 800 people queued at the Civic Offices to register during a specially extended office opening from 4pm to 7pm on Tuesday.
"We we're getting a lot of younger people but also some older people who had never voted before," she said.
The 14,000 extra voters will be added to the electorate in the five city constituencies of Dublin North West, Dublin Bay North, Dublin Central, Dublin South Central and Dublin Bay South.
Sinn Féin and other left wing parties have been running a voter registration drive on the doorsteps and through social media.
However, the extra voters are not expected to reach the figure of 20,000 achieved during the Abortion Referendum.
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