The Reverend Mihi Namana welcomed guests to the events centre, which she said had provided shelter for victims and emergency services workers and was a place "where the community came together as one".
Mr Mark said January 7 was "a time when the unimaginable happened" and assured the families that "your loved ones will never be forgotten in Carterton".
The mayor said that in the aftermath of the crash, emergency service workers had to deal with an event that "claimed the lives of people they knew".
Other citizens saw the accident and "many of them ran to the crash site", Mr Mark said.
Mr Mark said a "new greeting" had emerged in Carterton among those most closely involved with the tragedy, which was looking into the eyes and asking, "How are you?"
"We know that things like this do take a toll."
With the Balloons Over Wairarapa festival due to open this week, Mr Mark said "not one" family member had suggested the event not go ahead - and many wanted to "fly themselves as a tribute to their loved ones".
The Prime Minister and the Governor-General both spoke of the strength of people supporting each other in hard times, of which Mr Key said New Zealand has had "more than our fair share in the past couple of years".
Mr Key said the Government had a responsibility to find out what had gone wrong and would do so. Sir Jerry told Carterton that, "though the circumstances were tragic, your strength as a community was your greatest asset".